Bug in Queues?

im having difuculty implementing q’s and i think its due to a bug in the system.

Q:a rings ext 200 and 201.
-Say there are 5 callers in the q. 200 and 201 are ringing.
-200 Answeres caller1 and 201 is ringing.
-After 200 hangs up (with caller1) it wont ring again (with caller2) untill 201 answers a call (201 MUST answer for caller2 and 200 will only get caller3).
-In reality, 200 should start ringing (with caller2) as soon as it hangs up (with caller1) (btw, wrap-up-time = 0).

Is there an explination for this?