Parameters of selected argument do not match available arguments; MF does not return object.

Hi, guys! Pretty new to Mendix. We are creating a wizard page, and are tring to allow the user to pass through to subsequent pages. On our wizard page [Activities], we have a datasource leading to our MF entitled "Business_Model_Development.Act_MF". Each dataview (1-6), activates a MF. For example, Dataview 1 [Activities] activates the "Business_Model_Development.Act_MF". In the actual Act_MF, for example, in the parameter output the data type is "object", and Business_Model_Development.Activities is selected. We have included an exclusive split, with sequence flows leading to an activity (i.e., "Retrieve Activity List from Database"). The list is enumerated, and the sequence flow then leads to an end event. Finally, the MF also does not return an object. Any assistance would be greatfully appreciated.