Reply to Left hand sync button won't stay on

Firstly - just received my VCI-100 SE, and I love it. I am however having a slight issue.

My left hand sync button won't stay on - when I press it it comes on, but as soon as i release it it turns off. Any clues as to what could be causing this and how I can fix it?

I am using 1.3FW and 3.6.3 mapping.

Can't really understand why its happening - the button is working as the data light flashes when pressing and releasing the button. Perhaps I can update something in the mapping to resolve this?

Thanks

Woody