I finally found what was causing my repeated "no delivery" alarms. I recently upgraded to a Paradigm Revel pump (Good pump, horrible name) and when perusing the instruction manual. I found out that No Delivery alarms can sometimes be attributed to a problem with the battery connection. Sure enough, one of my reasons for upgrading was due to an aging (almost broken) battery cap. Still with the Silhouettes, but no more alarms. If you're getting repeated alarms you might want to check your battery connection. Thanks for all the input!
Yay for you!