Campaign says Filling Buffer for several seconds and then stops.
This is usually an issue with the Time Zone Settings in the Campaign software, under Options/Preferences/Time Zone Settings. If the list loaded has been told that it can't dial ET numbers unitl 12pm and it is only 11am where you are, the dialer will look for records that are not ET to dial. This is the filling buffer message. Check the Time Zone settings for correct times. Also it might be a good idea to randomize your lists when you import them. This can be done when importing a list under Options or when exporting a list, in the Export window. Randomizing the list will prevent it from have large clusters of the same time zone in the list, thus causing the Campaign software to "fill buffer" while it is looking for available records.
The other reason that this can happen is that the list has not bee imported correctly and the phone numbers are not in the primary phone number field. Re-import the list to fix this issue.
A third reason would be that the Campaign window itself needs to be reset. Simply close the Campaign window, open it back up again and select the list you want to dial with.