User-Exit/ Enahncement for LT03

Hi All,

I have a requirement like this:-

In case you have a partial picking a TO(TA Code-LT03) will also need to get the information, which Storage Unit type can be used.
The Functionallity needs to be extended for partial pickings.A partial picking is existing, when not a full pallet is picked

I need a enhancement which should determine the Storage Unit Type (SUT) based on the following logic

If storage unit type "PAL" (LTAP-LETYP) is being determined within the Transfer Order. and if LTAP-VSOLM = MLGN-LHMG1  then

LETYP = MLGN-LETY1 or if MLGN-LHMG1=9.999.999.999  then LETYP = MLGN-LETY1.

I tried with User Exit MWMTO007 and MWMTO001.

For MWMTO007, it did not trigger and for MWMTO001,  data is not being changed.

Can anybody suggest any user-exit/enhancement?

Regards

Sourav