distributor connectors camry 95

I am trying to discnnect the distributor to change the O ring. It has 2 conectors. the connector on the front side comes off easely. The one on the back (distributor wire ,page IG 34 repair maual). can't disconnect. Is there any trick?. Most of this connectors you just have to press end pull (like the one located in the front of the didtributor). Anything different with this one in the back?. Thanks.