You don't need an additional Step to do this. In the Message Popup step, you can configure the Status Expression field to be "Step.Result.ButtonHit==1?"Passed":"Failed". The step will pass if the 1st button was hit, and fail if any other button was hit. This might give you more useful information (LED Visual Inspection Step Fails vs. Test Fails).
If you still want to use an additional step to do this, the easiest way to do this is if the next step is if the additional step is a Pass/Fail test. In this case, you can change the DataSource property of the step to be "Step.Result.PassFail && RunState.Sequence.Main["Message Popup"].Result.ButtonHit == 1".
I would recommend the first approach, but the second approach can be done as well.
Allen P.
NI