Exception in accessing AX method through web Service (Application Integration Framework) in Ax 2012

Question

Here “retrieveCustomerIds” is my AX method which I am trying to access from webservice.

Definition of retrieveCustomerIds

[AifCollectionTypeAttribute('return', Types::String), SysEntryPointAttribute(False)]

public List retrieveCustomerIds()
{
List resultSet = new List(Types::String);

CustTable   custTable;
while select custTable

{
    resultSet.addEnd(custTable.AccountNum);
}

return resultSet;
}

Answer 1

I got success by changing the SPN to blank in my application config file.