Ovm_put_port with put method is blocking?

hi,
in my collector i have an ovm_put_port, with an unbounded size: rsp_put= new(“rsp_put”, this,0);
when i make the 1st rsp_put.put - its not blocking, but on the next rsp_put.put - the task halts.
how can i solve it?
btw, this port is connected to the driver’s ovm_get_port with unbounded size.
thx
ze’ev