Hi Janice,
Make sure you have maintained Communication Infotype(0105)- Sub type(0001).It should be same as PERNR and the gateway user id also same.
It should be like
GW User ID: 12345678
Communication Infotype(0105)- Sub type(0001): 12345678
ECC User ID:12345678
Give like this and test.
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Abdul Basha Shaik