Louu:
Here is my guide that I wrote, and it has worked for me on now 6 tanks...never fails:
http://cloudgodd.00bp.com/tank.html
the one thing I did not see you post is..
what is your source of Bacteria?
if you just using the air than it could take a while...
also you should be checking the ammonia, nitrite levels everyday you should maintain an ammonia lvl of 4 to 6 ppm (parts per million) if no nitrites are showing and 2 to 4 ppm of ammonia if nitrites are showing.
as soon as the nitrites and ammonia read 0 ppm in a 12 to 18 hour time span your cycle is done check the nitrate they should be HIGH around 60 to 180 ppm do a 90% water change, check the nitrates again if they are under 20 ppm let the tank relax for about 20 min and start adding fish.
make sure you are treating any water added to the tank before you add it.