i Got a WRX Import which has had the automatic box replaced about a month ago it worked ok for a while then i have the same problem
again now when she goes to shift from second to third gear it sends the rev counter off the scale and she goes no where, tranmission fliud is ok what could it be ????? bad box ? or what? help please!

 

Sounds like the second gear bands got tightened and now they are stretched again