I have a 2007 Mercury Milan and it won t let me play music on the aux

What is your question?

I plug in the aux cord and phone but it won t go to "line in". The only thing that shows when I press the aux button is the XM radio stations 1, 2, and 3 but not "line in". How do I get it to go to line in so I can play my music?! HELP PLEASE!