Problem with Wave mode, i think its bug .. Please Help!

When i play wave mode i select my class card and start the game, after i reach Lv 5 it suposed to let me use my class weapon but it never let me do that exept Juggernaut class, in Juggernaut when i reach Lv 5 i see the activation icon at the left bottom of the screen with word "F" and when i press F my character gets Juggernaut's effect, i thought its a problem on my game client and i should download it and update it again thats why i created another new account to check the wave mode with it but it works fine with every class, so whats the problem at my account ? and i see some players gets the same problem, Please help!

Here is some screen shots

http://upload.traidnt.net/upfiles/njB60276.gif

http://upload.traidnt.net/upfiles/LsH60361.gif

http://upload.traidnt.net/upfiles/F0V60441.gif

http://upload.traidnt.net/upfiles/KLh60481.gif