Question About IDOC ADAPTER

I test a scenario as file->xi->IDOC->R/3

and another scenario as R/3->IDOC->XI-file

i think, it should be two Communication channel

to R/3,one is Receiver another is Sender

But when i create the channel ,after select the adapter

tyep as IDOC, i can not select the Channel as a Sender

Can only set it as a Receiver

why?

and when i test the first scenario , the flowing error

appers(my test idoc message is 'CREMAS03':

<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>

- <!-- Call Adapter

-->

- http://sap.com/xi/XI/Message/30" xmlns:SOAP=" http://schemas.xmlsoap.org/soap/envelope/" SOAP:mustUnderstand="">

<SAP:Category>XIAdapter</SAP:Category>

<SAP:Code area="IDOC_ADAPTER">ATTRIBUTE_IDOC_RUNTIME</SAP:Code>

<SAP:P1>I:IDOC_ADAPTER:209 66609E10320A11D9ABCB000F1F6BBAD1 E1LFA1M</SAP:P1>

<SAP:P2 />

<SAP:P3 />

<SAP:P4 />

<SAP:AdditionalText />

<SAP:ApplicationFaultMessage namespace="" />

<SAP:Stack>Fehler: I:IDOC_ADAPTER:209 66609E10320A11D9ABCB000F1F6BBAD1 E1LFA1M</SAP:Stack>

<SAP:Retry>M</SAP:Retry>

</SAP:Error>

all of setting seems fine.