Message mapping error in UDF of PI 7.31

Hi All,

I have migrated a scenario in PI 7.31 from a old XI system.

In that scenarion,there was a UDF called duplicatefile check which basically declares an object of DuplicateFileValidation.and then by using the object it calls a method "validation " which is already declared in the class DuplicateFileValidation.

The udf duplicatefile check is like that:

String response = null;
AbstractTrace trace = container.getTrace();

DuplicateFileValidation  instance = new DuplicateFileValidation();

response  = instance.validation(service[0],communicationchannel[0] ,trace,container);

result.addValue(response);

I have already imported the DuplicateFileValidation as an imported archive in the fubction tab of message mapping

In older version It was working fine.but in 7.31 while activating the message mapping an Error comes:

Can anyone have any idea how to solve this:

Pls help me