Commitment Method

Could someone give me a reason why Commitment Method 3 (Lot Expiration Date) does not function properly and possible ways to get it working. When allocating stock the program seems to 'give up' (It appears the lot master reaches a certain volume) searching and does not then allocate according to expiration date. We are now having to use Commitment Method 1 (Location with Most Quantity) which is ok but we need to be ideally running Lot Expiration Date. I have checked the knowledge garden to no avail.

Any help would be greatly appreciated.

Cheers

J