Yes, Audrabolster is correct - if you had a trip to WDW on the same PP account with a DLR trip, and especially if the WDW pictures were taken and added to the PP account AFTER the DLR pictures were taken and added, that is likely the problem. Otherwise, if the WDW photos are added first and the DLR photos last, the price should adjust at checkout to the DLR price of $59.95 + $7.00 shipping price.
Also, did you pre-order a CD for DLR (which is not something that is recommended to do for DLR CD's)? If you pre-ordered AND had WDW pictures on the same CD as DLR photos, that could be throwing everything off.