No class def found for the first time of accessing the class even when the related jar is available

Question

Sample code snippet.

class Sample extends Test1 ,Test2
{
...
}

The class Sample is in x_util.jar and the class Test2 is in y_const.jar. Both the jars are in the same lib folder of JBoss.

Problem

When I am trying to access the class Sample for the first time it is throwing the error

No Class def found

saying Test2 is not defined.

If I am accessing it again then it is working fine.

Please suggest.