Help with a Macro

I am trying to build a macro that would let me accomplish the following.

I want to use the Range tool to select a range, then split that range then must the range. I can;t seem to figure oiut how to highlight the newly created range in such a way as to get the mute command to actually mute the new range.

I hope this is clearly articulated. Thanks in advance for any thoughts.

Best,

Jay