How do i fix my hydraulic lift gate?

i have an older chevy truck that has an older monarch lift gate. i had the motor pump and the rest of the unit rebuilt. after i picked it up and put it in the way i took it out it wont work. there is power. the switch is working fine. when you try to bring it up is gives it a good shot and tenses up but it doesnt want to pull it up. its trying but everything i do i cant get it to go up. i had hydraulic oil and drained that out because the company says that tranny fluid is better to use so i put that in. i have beed told to bleed it but im not sure if i did it right whats the best way? the whole motor pump and anything connected to that is new. thefluid line seemed fine. is there a bleeded? how do you think i could fix this. i need it to work badly, im 17 on a budget useing this truck daily its killing me. any help would be awesome thanks