subaru9696

hello Everyone. I just purchased my second subaru yesterday, this time a 96 legacy wagon, automatic transmission. I am going through and doing a full tune up, new sparks etc. I have run into a spot of trouble though. After draining the transmission fluid (which looks like it has never been changed), I proceeded to add fresh fluid, however it is not draining correctly back into the pan. As far as I can tell, there are no blockages. However am I missing a vent somewhere? there is no fluid entering the drain pan, nor can i get any to come out of the plug. Dropping the pan, i can't see anything thats interupting flow. Now with little tranmission fluid running through the system the car is stuck dead in the driveway, blocking my way out. Any help would be appreciated, thanks K