Anel-slo, I don't know which trigger you are using, but I've actually found the Yongnuo RF-602 triggers to be more reliable with my Canon flashes than my Pocket Wizards! (The PW are subject to more radio interference). The RF-602 is now my "cheap trigger" of choice and never misfires for me.
If you are interested, I have a video test/review of the RF-602 on YouTube here:
http://www.youtube.com/watch?v=s5shvFGUf3g
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