No Power to Stereo. Checked Fuses

[dlicious]

Hi first post on this forum as im completely stuck.

My wifes 2004 Beetle is causing me problems with the stereo. I was updatting the original stereo with a sony aftermarket unit. I cant seem to get any power to either of the units.

Here is what I have checked:

Both fuses in the beetle (37 & 42) both are fine.
Fuses on the head units themselves both are fine
Used a mutimeter to see if there is a permanent live and there isnt one there.

Up until a coule of weeks ago everything was working fine.

Can anyone give me some advice please as my wife has no music :-(

Thanks