I'm having difficulty sending a message while within my ADC interrupt. I can send a message just fine when I'm in a thread using the same mailbox. However, within the interrupt, osMessagePut returns osErrorParameter. When stepping through the code, I can see that it returns that if (((P_MCB)queue_id)->cb_type != MCB). In the debugger, I can clearly see that queue_id->cb_type == 1, which equals MCB when I look up the definition of MCB. I'm not sure what's going on here as RTX is compiled as a library so I can't see exactly what's going on. Any suggestions? Thanks!