Change Batch Valuation type during Order confirmation

Dear Experts,

We have activated split valuation and the valuation category is X Automat.(Batch). But, During production order confirmation, I need to change the valuation type to first 4 digits of the batch number.

For Eg, if batch number is 1314010043, valuation type should be 1314.

I tried SAPLV1ZN, EXIT_SAPLV01Z_013 but its not triggering during production order confirmation. Pls suggest any Exit / BAdI.

Thanks

Sudeep.