How to use api to retrieve MObject?

[Anonymous]

I used GetMObject operation.
Type = "Opportunity"
AttrName = "Role"
Comparison = "EQ"
AttrValue = "Decision Maker"

I want to get the Opportunity whose Role  is Decision Maker.
But i got the error.

<msg>TIBCO-BW-PALETTE-MARKETO-500002: There was a problem with your request. Marketo returned error code Internal error. Detail Message:attribute map field with key Role not found-

{ActivityName=Retrieve, ProcessName=test.Process1, ModuleName=Test}</msg>

I would be thankful is you can help me.

[John_M]

Can you provide a copy of your input XML shape?