diff --git a/src/core/loader.h b/src/core/loader.h
index 27a6fda55b..aa292418c4 100644
--- a/src/core/loader.h
+++ b/src/core/loader.h
@@ -21,11 +21,10 @@ class BaseLoader : public T {
     if (handle_ == NULL) return NULL;
 
     fun_t *f = (fun_t*) dlsym(handle_, fun_name);
-    if (f == NULL) {
+    if ((to_check_symb_ == true) && (f == NULL)) {
       fprintf(stderr, "roctracer: symbol lookup '%s' failed: \"%s\"\n", fun_name, dlerror());
       abort();
     }
-    dlerror();
     return f;
   }
 
@@ -48,11 +47,10 @@ class BaseLoader : public T {
   BaseLoader() {
     const int flags = (to_load_ == true) ? RTLD_LAZY : RTLD_LAZY|RTLD_NOLOAD;
     handle_ = dlopen(lib_name_, flags);
-    if ((to_check_ == true) && (handle_ == NULL)) {
+    if ((to_check_open_ == true) && (handle_ == NULL)) {
       fprintf(stderr, "roctracer: Loading '%s' failed, %s\n", lib_name_, dlerror());
       abort();
     }
-    dlerror();
 
     T::init(this);
   }
@@ -62,7 +60,8 @@ class BaseLoader : public T {
   }
 
   static bool to_load_;
-  static bool to_check_;
+  static bool to_check_open_;
+  static bool to_check_symb_;
 
   static mutex_t mutex_;
   static const char* lib_name_;
@@ -203,13 +202,15 @@ typedef BaseLoader<RocTxApi> RocTxLoader;
   template<class T> typename roctracer::BaseLoader<T>::mutex_t roctracer::BaseLoader<T>::mutex_; \
   template<class T> std::atomic<roctracer::BaseLoader<T>*> roctracer::BaseLoader<T>::instance_{}; \
   template<class T> bool roctracer::BaseLoader<T>::to_load_ = false; \
-  template<class T> bool roctracer::BaseLoader<T>::to_check_ = true; \
+  template<class T> bool roctracer::BaseLoader<T>::to_check_open_ = true; \
+  template<class T> bool roctracer::BaseLoader<T>::to_check_symb_ = true; \
   template<> const char* roctracer::RocpLoader::lib_name_ = "librocprofiler64.so"; \
-  template<> bool roctracer::RocpLoader::to_load_ = true; \
+  template<> bool roctracer::RocpLoader::to_check_open_ = false; \
+  template<> bool roctracer::RocpLoader::to_check_symb_ = false; \
   template<> const char* roctracer::HipLoader::lib_name_ = "libhip_hcc.so"; \
-  template<> bool roctracer::HipLoader::to_check_ = false; \
+  template<> bool roctracer::HipLoader::to_check_open_ = false; \
   template<> const char* roctracer::HccLoader::lib_name_ = "libmcwamp.so"; \
-  template<> bool roctracer::HccLoader::to_check_ = false; \
+  template<> bool roctracer::HccLoader::to_check_open_ = false; \
   template<> const char* roctracer::KfdLoader::lib_name_ = "libkfdwrapper64.so"; \
   template<> const char* roctracer::RocTxLoader::lib_name_ = "libroctx64.so"; \
   template<> bool roctracer::RocTxLoader::to_load_ = true;
diff --git a/src/core/roctracer.cpp b/src/core/roctracer.cpp
index 846648dd45..37aa0dc9eb 100644
--- a/src/core/roctracer.cpp
+++ b/src/core/roctracer.cpp
@@ -649,11 +649,13 @@ static roctracer_status_t roctracer_enable_callback_fun(
     }
     case ACTIVITY_DOMAIN_HSA_OPS: break;
     case ACTIVITY_DOMAIN_HSA_API: {
+#if 0
       if (op == HSA_API_ID_DISPATCH) {
         const bool succ = roctracer::RocpLoader::Instance().RegisterApiCallback(op, (void*)callback, user_data);
         if (succ == false) HCC_EXC_RAISING(ROCTRACER_STATUS_HSA_ERR, "HSA::EnableActivityCallback error(" << op << ") failed");
         break;
       }
+#endif
       roctracer::hsa_support::cb_table.set(op, callback, user_data);
       break;
     }
@@ -735,11 +737,14 @@ static roctracer_status_t roctracer_disable_callback_fun(
     }
     case ACTIVITY_DOMAIN_HSA_OPS: break;
     case ACTIVITY_DOMAIN_HSA_API: {
+#if 0
       if (op == HSA_API_ID_DISPATCH) {
         const bool succ = roctracer::RocpLoader::Instance().RemoveApiCallback(op);
         if (succ == false) HCC_EXC_RAISING(ROCTRACER_STATUS_HSA_ERR, "HSA::RemoveActivityCallback error(" << op << ") failed");
         break;
       }
+#endif
+      roctracer::hsa_support::cb_table.set(op, NULL, NULL);
       break;
     }
     case ACTIVITY_DOMAIN_HCC_OPS: break;
@@ -848,10 +853,14 @@ static roctracer_status_t roctracer_enable_activity_fun(
         roctracer::hsa_support::async_copy_callback_enabled = true;
       } else {
         const bool init_phase = (roctracer::RocpLoader::GetRef() == NULL);
+        if (roctracer::RocpLoader::Instance().InitActivityCallback == NULL) break;
         if (init_phase == true) {
           roctracer::RocpLoader::Instance().InitActivityCallback((void*)roctracer::HSA_AsyncActivityCallback,
                                                                  (void*)pool);
         }
+        if (roctracer::RocpLoader::Instance().EnableActivityCallback == NULL) {
+          EXC_RAISING(ROCTRACER_STATUS_ERROR, "EnableActivityCallback not found");
+        }
         const bool succ = roctracer::RocpLoader::Instance().EnableActivityCallback(op, true);
         if (succ == false) HCC_EXC_RAISING(ROCTRACER_STATUS_HSA_ERR, "HSA::EnableActivityCallback error");
       }
@@ -944,6 +953,10 @@ static roctracer_status_t roctracer_disable_activity_fun(
       if (op == HSA_OP_ID_COPY) {
         roctracer::hsa_support::async_copy_callback_enabled = true;
       } else {
+        if (roctracer::RocpLoader::Instance().InitActivityCallback == NULL) break;
+        if (roctracer::RocpLoader::Instance().EnableActivityCallback == NULL) {
+          EXC_RAISING(ROCTRACER_STATUS_ERROR, "EnableActivityCallback not found");
+        }
         const bool succ = roctracer::RocpLoader::Instance().EnableActivityCallback(op, false);
         if (succ == false) HCC_EXC_RAISING(ROCTRACER_STATUS_HSA_ERR, "HSA::EnableActivityCallback(false) error, op(" << op << ")");
       }
diff --git a/test/MatrixTranspose_test/MatrixTranspose.cpp b/test/MatrixTranspose_test/MatrixTranspose.cpp
index 3877a4dead..14e3b847c0 100644
--- a/test/MatrixTranspose_test/MatrixTranspose.cpp
+++ b/test/MatrixTranspose_test/MatrixTranspose.cpp
@@ -312,9 +312,9 @@ void activity_callback(const char* begin, const char* end, void* arg) {
       if (record->op == HIP_OP_ID_COPY) fprintf(stdout, " bytes(0x%zx)", record->bytes);
     } else if (record->domain == ACTIVITY_DOMAIN_HSA_OPS) {
       fprintf(stdout, " se(%u) cycle(%lu) pc(%lx)",
-        record->ps_sample.se,
-        record->ps_sample.cycle,
-        record->ps_sample.pc
+        record->pc_sample.se,
+        record->pc_sample.cycle,
+        record->pc_sample.pc
       );
     } else if (record->domain == ACTIVITY_DOMAIN_EXT_API) {
       fprintf(stdout, " external_id(%lu)",
@@ -350,7 +350,6 @@ void init_tracing() {
   ROCTRACER_CALL(roctracer_enable_op_activity(ACTIVITY_DOMAIN_HSA_OPS, HSA_OP_ID_PCSAMPLE));
   // Enable KFD API tracing
   ROCTRACER_CALL(roctracer_enable_domain_callback(ACTIVITY_DOMAIN_KFD_API, api_callback, NULL));
-  ROCTRACER_CALL(roctracer_enable_domain_activity(ACTIVITY_DOMAIN_KFD_API));
   // Enable rocTX
   ROCTRACER_CALL(roctracer_enable_domain_callback(ACTIVITY_DOMAIN_ROCTX, api_callback, NULL));
 }
@@ -368,7 +367,9 @@ void stop_tracing() {
   ROCTRACER_CALL(roctracer_disable_domain_callback(ACTIVITY_DOMAIN_HIP_API));
   ROCTRACER_CALL(roctracer_disable_domain_activity(ACTIVITY_DOMAIN_HIP_API));
   ROCTRACER_CALL(roctracer_disable_domain_activity(ACTIVITY_DOMAIN_HCC_OPS));
-  ROCTRACER_CALL(roctracer_disable_domain_activity(ACTIVITY_DOMAIN_KFD_API));
+  ROCTRACER_CALL(roctracer_disable_domain_activity(ACTIVITY_DOMAIN_HSA_OPS));
+  ROCTRACER_CALL(roctracer_disable_domain_callback(ACTIVITY_DOMAIN_KFD_API));
+  ROCTRACER_CALL(roctracer_disable_domain_callback(ACTIVITY_DOMAIN_ROCTX));
   ROCTRACER_CALL(roctracer_flush_activity());
   printf("# STOP  #############################\n");
 }