Hi Manjula

May i know your sur name?

The best thing to do is provide the developer the instances that produced a Bug.Give him all the Input data and also take a snapshot of the Bug and attach the same with the Defect.

Steps to prove it as a bug are:

1. Tester should show in which scenario particular test case is failing

2. Tester should show the 'Reproducible steps' that how a scenario is failing

3. Tester should prove that as a bug as per the requirements when it is developed in the application even though that is not specified in the requirement document or when it is developed diferently

4. Tester should show all the possible ways to prove it as a bug

The following steps are useful for a tester to prove it as a bug:

1. Tetser should show in which scenario particular bug occurs

2. Tester should show the reproducible steps for causing the bug

3. Tester should show whether the bug ocurrs by not satisfying the customers requirment or it is developed in the application even though requirement is not specified in the requirement document

4. Tester should discuss about all the posible ways with the Developer and he should take this discussion to higher authority

Tester has to prepare a bug report which should contain all the details such as In what environment (In which operating system etc) the bug is coming Reproducing steps ( How to start the application etc) etc. It will be very good if any related screen shots have been attached which gives clear idea to the developer.