Error (value is not an interger)

[DarrylWPerry]

I installed the Simple Donate extension (Wordpress Fluida theme) on my website (DarrylWPerry.com), and when I try to test it, I get the following error:
Sorry, due to an error, we are unable to fulfill your request at the moment. You may want to contact your administrator or service provider with more details about what action you were performing when this occurred.
One of parameters (value: ) is not of the type Integer

Please help!