I am developing a program in VBA Ecxel2010 (stored as a xlsm-file). I use the AxctiveX Component SComm32 to administrate Serial Communication. I run the 64 bit version of Excel 2010. Sometimes when storing an error occurs. It says SComm, Run-time error. Device I/O error. Can anybody tell me what is the problem? Could the SComm lead to the problem?