MVC JTABLE has a Foreign key Issue?

Question

 

Hi Friends

 

In my application i am using 2 Jtables in mvc3. 1 for parent and other for child table. on click of a parent table row in Jtable i want to display corresponding values in child table.

I will display the parent records .But my problem is If the parent table will have the child records in database then whole Parent table will not be displayed and getting the error like this for both the tables

Error: An error occured while communicating to the server.

am getting this error for list action method in the entity related classes