Hi Powerhousefitness and thank you for the information you have been providing me about this issue. An issue has been located and reported for a fix in a future CMS release. You can track its progress here.
To provide some further context for any other users experiencing this issue, the error is returned if you set an Ad Campaign to have the same start and end date. This is scheduled to be resolved in the 4.0.5 CMS release. In the meantime, please use a start and end date that are not on the same day.