You probably have one of the following situations:
I'm assuming you have a microflow that you'd simply like to execute, without parameters. In that case you need to set the "Invoke on" property of the invoke button to "None", instead of the default "Selection". Alternatively, if you have it as a before/after commit action, you must add a parameter to the microflow. This parameter must have the same type as the metaobject to which you have linked the action.
If you are trying to learn how to model I'd suggest you start at the Learn Mendix page. That has links to all the newest learning material, including an updated Microflows page.
Also I think the error is because your input parameter object does not match the object you get passed when the microflow is executed, say when using an invoke button.
If you put an invoke button on a datagrid that shows all Test.Data objects, your microflow needs to have 1 input parameter, a Test.Data object; no more, no less.