problem with mutex

My question is related to semaphores. I am working on STM32VL_DISCOVERY Board, using the ATOLLIC TRUE STUDIO with FRE RTOS. I looked up the mutex semaphore in the API reference, and used them in my program, and compiled it. Got an error complaining about an “undefined reference to xQueueCreateMutex”. If I drop in a binary semaphore is compiles just fine.   Again, I’m sure I’m just missing something simple.  Any ideas?

problem with mutex

Set configUSE_MUTEXES to 1 in FreeRTOSConfig.h. Regards.