Object reference not set to an instance of an object

Hi all,
When i run my application on local host it run perfect without geting any error.
But when i run same application on serevr i geting this error.  
Server Error in '/' Application. Object reference not set to an instance of an object. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.NullReferenceExcep ...