[Users] switch - pseudo vars

Hello, I'm using openser 1.1.0 I'd like to make a dinamic routing, the plan is radius set an avp, which contains the routeid, but my config is bad, and i don't know what can be the problem route($avp(i:20)); don't work so i tryied this way: switch($avp(i:20)) { case 0: route(0); break; case 1: route(1); break; case 2: route(2); break; } but this is bad too, can anybody give me an advice? the problem is in the line "switch($avp(i:20)) {" i guess, but switch can accept pseudo vars, so i don't kow what the problem caould be? Thanks any help, Tamas