idoc status error 37 in sender and 51 in recieving system

i m new to ale idoc n created 2 clients 910(sender system) and 800(reciever system)

all connections are well i got status message 03 and 30 and 01 but along with it i m getting one more idoc genersted and status as 37 . idoc no. 50 as 03 30 and 01 and idoc 51 as 37 . in sender system n inreciever system i m not getting idoc.after sumtim i m getting them n error status as 51 .two idocs are generated simultanously.

does the port name we21 should be same i m using same port name currently .

clnt910 --rfc800 destination client 800 (sender system).

clnt800 --rfc800 destination client 910 (reciever system).

when i m changing the port name i m getting error status as 29 .

we20 both the partner profile are active