subclass instance not created during runtime

Hi Experts,

For an existing standard class a subclass was created and during runtime the me object reference points to the subclass name there by allowing the subclass additional/custom methods to be triggered.

We have done service pack upgrade in the system and during runtime I find the subclass does not exist in the me object reference due to which the custom code in the subclass is not being called.

How do I fix the above issue so that and subclass instance is created by the superclass during runtime?