Park Call

Hi,
a good day to you all.
i have this problem regarding park calls.
we have 4 asterisk box which are setup in load balancing with each other.
now here is the problem for example AST1 is where the DID is setup then the Agent is in logged on the same box (AST1) the park call works perfectly. but if the Agent is logged on AST2 thats where tha problem occurs, for some reason the Agent cant put the caller on hold(Park Call) he/she can press the Park Call button but nothing happens they can still hear each other.
any ideas?
in case this would help
Asterisk 1.2
Astguiclient 2.0.4
Thanks in Advance.
a good day to you all.
i have this problem regarding park calls.
we have 4 asterisk box which are setup in load balancing with each other.
now here is the problem for example AST1 is where the DID is setup then the Agent is in logged on the same box (AST1) the park call works perfectly. but if the Agent is logged on AST2 thats where tha problem occurs, for some reason the Agent cant put the caller on hold(Park Call) he/she can press the Park Call button but nothing happens they can still hear each other.
any ideas?
in case this would help
Asterisk 1.2
Astguiclient 2.0.4
Thanks in Advance.