cannot jailbreak

[bonehead]

hi all
i have a iphone 3g that i have tried to jailbreak it is on 4.2.1,i have tried limera1n,greenpois0n,blackra1n,redsnow i go through the procedure of button pressesredsnow says device not supported,all others just stop working,any ideas
cheers

[fijiman]

[ame=http://www.youtube.com/watch?v=MSUr3S2Jm5c]GreenPoison RC6.1 Untethered 4.2.1 Jailbreak iPhone, iPod Touch, iPad & Apple Tv2 - YouTube[/ame]

[smirnoff_rules]

I had one the other day and couldnt get into Dfu mode for the life of me , l gave up and had to fit a screen to it anyway . Then noticed the connection on the home button was poor and cleaned that and replaced screen , refitted and when into Dfu mode first time ? L think the home button was working but only for a second then going off , u wouldn't notice using the phone as u only press once at a time

[bonehead]

cheers for that never thought of it being faulty home button, going on hols tomorrow so not starting on it now,but will have a go when i get back
once again thanks