How to change existing batch determination.

Hi experts;

I have an issue with changing the existing batch determination for a production order components. I searched a lot in the forum, but failed to resolve the problem.

Following are the existing configuration settings;

Condition type : Order type / Plant / Material

Batch Class  characteristic value - MCH1_LWEDT

Sort sequence characteristic value - MCH1_LWEDT

Instead of sorting all batches on above conditions, i want to sort batches on the basis of expiry dates.Then i have changed the class and sort sequence as below.

Condition type : Order type / plant / Material

Batch Class characteristic value : LOBM_VFDAT

Sort sequence characteristic value : LOBM_VFDAT

Then i changed the all components materials in COB2 and tested. But it is not working for some materials.

Could you please explain me the possible reasons for the error and do i need to do any master data changes?

Thanks & Regards;

Malka