I wrote a small program which uses the MSComm32.ocx to transfert data from serial port. On my computer, it works very weel, but when I want to execute it on a other computer, an error message tells me that a not supported operation was tempted. This error occurs each time that the program performs the UpdateData() function. I used the class wizard to map a control variable to the ocx. My question is why it is working on my PC and not on other? I tried to compile my app whith the MFC in a static library but I got the same error.