I just changed my front break caliper and am having trouble with try to bleed it. The fluid goes through to the caliper, but when I continue to pull the break lever nothing happens. I am using the bleeder valve and the fluid comes out when I squeeze the brake. What am I doing wrong? Do I have to use DOT 5 or can I use DOT 4?

 

Not sure what year/model you're working on (nobody ever says!), but you might check the Forum hints on brake bleeding Here.