Sequence Contains more than one element.

Question

Hi guys, I am using EF in my application. Initially, the database wasn't created yet in the DB server, instead my application will create it based on my model.  So here's the problem, when I run the program, I'm encountering this error

Count '_temp.Count' threw an exception of type 'System.InvalidOperationException' int {System.InvalidOperationException}
Sequence Contains more than one element.

I need your help guys. Thanks in advance.