Where they really hard to put back on? If there was still pressure in the hyd lines when you reconnected them, they may not have released inside even though they feel and/or look connected.
Are you sure you got them on in the right direction - sometimes they can get swapped if your tractor has the same fittings in the same direction on all the lines
I have had to manually release the pressure in the lines to get them to plug back together correctly. I did this by tapping the "pin" on the connector to release the pressure.