thanks a lot for the reply Paul, I changed the input parameters to the method from reference parameters to pointer parameters. It did not work ,it failed with same error. Then we thought of trying using a simple data type than class. We tried to send a string using reference it failed with

"External component has thrown an exception,System.Runtime.InteropServices.SEHException: External component has thrown an exception"

Then as you suggested, we changed the input parameter to pointer input, . it worked for string. Now we are guessing, there is some issue with our DataCollectorClass. Any Thoughts from you will be really helpful. The class has many fields, if required i will post the whole code.

Thanks Again
Naresh