#20 modbus not communicate

[nidhi]

Dear sir,
I have downloaded modRSSim application and it was working with my application very well. But now it is not communicating with my application. I don't remember if any network setting I have changed on my pc. I am using mod tcp for modbus communication.
I also have modSim32 application which works with my application but not modRSSim. What can be the cause.
I can observe traffic but my application reports error as "Unable to read data from the transport connection: A non-blocking socket operation could not be completed immediately."
My application is in dotnet 2008.