painting weights
 

im rigging a character using maya 6 and am having trouble painting weights. After I bind my skeleton to my skin and open the paint skin weights tool, anything that i change, whether i add, smooth,scale or replace. resets after i click off the tool or click on another joint.

Is there something i need to do to make the changes stick?

Also, after i use the tool my skin no longer is bound to my skeleton?

can anyone help?