How to use that library if it is so bad documented? We do alot of serial programing. At the end it pays 10x using a good commercial library with technical support. We successfuly replaced MSComm with SuperCom ActiveX and it also solved us a lot other issues we had with Bluetooth devices.

Most likely, this is your problem: CString CXbeefixedDlg::getCurStrInCombobox(const CComBoBox &a) Instead of CComBoBox, it should be CComboBox Hope that helps. Karl - WK5M PP-ASEL-IA (N43CS) PGP Key: 0xDB02E193 PGP Key Fingerprint: 8F06 5A2E 2735 892B 821C 871A 0411 94EA DB02 E193