Custom class works differently when invoked from batch

Hi,

I made a small change in my custom class that runs on a schedule. I tested the code by running it from menu  but when the same class is invoked from scheduled batch it is still using old code. The batch runs under different user account. I loged in as that user, reseted usage data, ran that class again and it worked flawlessly but when scheduled it fails.

How to fix this?  Do I need to recompile whole application?

Thank you,
Michael