Mkvtoolnix unable to functioning as I need

I’ve got a video and I am required to add additional vocals, particularly commentary to the video but I’ve got no idea how to do it. Thanks to Google as it suggested me to get hand on the mkvtoolnix software. Nevertheless, the time I click on the ‘mmg.exe’ it delivers the following error message.
"The application was unable to start correctly (0xc0000005). Click OK to close the application. ”
Please help me?
