I dont think its the fluid....
why did u use the gearbox breather hole to fill it up ? Probably a big gulp got stuck in there with a big airbubble and blew it all out again = not enough fluid. There is a few good resources about PROPERLY filling up gearbox - including the DIY i did very recently - look -

http://www.ozhonda.com/forum/showthread.php?t=58596

+1 stupidity rep to you lol.