I think you may have to take the boat or monorail over to the Transportation and Ticket Center and catch a bus from there. The only buses actually at the MK gates are to resorts, and all buses from MK to other parks are technically from the TTC. Or you can walk over to the Contemporary and catch a bus to DAK from there. For whatever reason, although you can get a direct bus from DAK to MK, you can't do the reverse, MK to DAK, without a stop at TTC.