I'm going slightly mad you guys .. how can I get alpha chanel on blocks ?

you can't. at least for transparency and not in a6. use models instead.

so i wan't to make a fence, how can i make my grid fence texture be transparent only in the right plases on the model texture? anyone got a walktru ?

use a model. make the grid aout of 2 triangles and texture it with a alpha channel map. tuts on alpha channels:

http://www.coniserver.net/wiki/index.php/The_Alpha_Channel

thanks man ^^