Cant define incremental backup job

Ghost 15 won't let me define an incremental backup.  The selection is in grey.  A note at the bottom says a drive is already defined in an incremental.  I have deleted all backup jobs, but still get the same result.  I uninstalled and reinstalled Ghost - still the same result.  I'm running Win7, 64bit.  I did get an error message on the uninstall, and on the reinstall  "Error:  Failed to have access running.  Install VSSWProvider function in MSInstallVSSProvider function".