How can I use OnMouseDown and a button click in the same scene?

@Mohobie answered a question with "I recently encountered a loss of my working modal. I found that it was due to the mouse being locked by another script that made my click not actually fire on the button. Just a thought for anyone who might be looking." I think my button isn't working because I'm using OnMouseDown in another script, and it isn't registering my click on the button as a button clcik.