Greenpois0n should work. Limera1n won't. What types of problems are you experiencing with greenpois0n? It can require a few tries. I just did 5 iPhone 4's last night with it and it worked, it was just hard to get some of them to go through. I had to repeatedly follow the timer on 3 of the devices at least 3 or 4 times per device in a row before it worked.
I think I know the problem. When you set it into DFU with the timer and it let's you click jailbreak, don't let go of the home button. Just keep holding home and click jailbreak, and hold it until all the codes go away and shows the apple logo.
Oh by the way, it would help if you actually set your phone into dfu mode first before opening greenpois0n. Hold the home button, open gp and instead of the timer it will just let you click jailbreak.