brake problem

Hello, I have a problem with an Opel Corsa truck that changed the gums of the rear wheels because it had the drum wet in oil but we could not place the pedal hard, so we changed the gomites to the brake pump and how it is placed a little hard but we set the engine and it is released all the little pressure that we bleed with the engine on and nothing does not take pressure.
I hope the problem is understood, if someone has happened to him, I would appreciate it to comment, thank you now

Try to purify your pump and your rear wheels starting with the farthest of the pump and then continue with the front, you checked that the cylinders of the interior were not scratched?

I was impeccable, that's why I thought I was not going to have a problem but I'm going to thumb it in the way you tell me and if it doesn't work to buy the pump because no oil comes out anywhere that we could detect that it is not the pump.