brake chamber leaking from rear when brakes applied

i just installed the new brake chambers on the single drive axle on my truck. I go to apply brakes and i notice air is leaking out of the driver side chamber rear of the pot. The slack adjuster is moving . The other brake chamber on the passanger side drive axle is not moving and no air is escaping. While applying brakes the air continues to expel out to the rear of the brake chamber until i lose all air pressure. The air brakes also do not appear to be holding the truck very strudy when in park (I can still roll forward or backwards with parking brake on). The parking brake issue was known before i installed t he new chambers... did i do a installation wrong (yes i'm a total newbie) or is there another problem with the air system or rear part of the chamber(s?)?

 

the one that is leaking, is expelling air out of the REAR of the chamber (i only installed the front half brand new) the entire time i hold my foot on the brake. It also has the arm of the slack adjuster moving, the arm on the other brake chamber is not moving, nor is it leaking any air. What does this mean? The front halfs of the chambers are brand new on both sides. Did i install it wrong? is the rear part broken? Did I uncage incorrectly? somehow buy a faulty one?

 

what is my frist step? is the other chamber installed correctly? (the one not leaking) yes i can wtih little difficulty drive forward despite the parking brake on. That is why i put on the 2 new chambers.

 

sorry i just looked at a picture and can use better terms now. The air is leaking out of the "service chamber" of my driver side rear brake chamber. I believe i only installed the "park chamber" (front part of the brake chamber) on both passanger and driver side rear axle. Air is leaking out of the push rod area on the service chamber when brakes applied on just the one brake chamber. The push rod is moving on that brake chamber but NOT moving on the other chamber that is not leaking air.

 

Sorry for my ignorance of terms, the service chamber is old, the park chamber is new.