Capture device not working via TV

[Jukebag]

Hi, I have an external capture USB device (Climax Digital) that I regularly use to capture from VHS tapes to my laptops, one is an Acer running on Windows XP and the other a Toshiba Satelitte running on Windows 8.1 (64 bit). Hooking the device up to my older laptop I have no real issues in viewing and capture from an external recorder, and up until recently I have been able to connect my Toshiba laptop up to a TV (using a SCART to composite connection) and using a capture software. But now when I try to do this nothing appears on screen except either a blank screen or horizontal signal lines. When I try to open a particular capture programme (such as Debut, which isn't great at capturing steady video) a "capture device not recognised" messge appears.

Anyone know what's causing this?.