CompuServe Messages

I have had previous success using the Grab screen capture utility to capture screens created in Harvard Graphics But recently when I try to use it, it appears to capture the image but when you retrieve the GRAB.WPG file it is blank and only takes up about 102 bytes every time. Repeated ventures have yielded the same result. Any suggestions? Also, how do I set up the VDI driver for saving HG images that WP can retrieve? Any help is greatly appreciated.