I've upgraded to Knoppix 7.2 and started to customize it to my liking, but one of my standard customizations is to install several Firefox extensions into Iceweasel, including Add-on Update Checker. This extension now tells me that NoScript and FoxyProxy (which both come preinstalled in Knoppix 7.2) already need to be updated, but every attempt I've made to update them has failed. This defeats the purpose of Add-on Update Checker somewhat, because now the "update needed" icon is always lit.

Does anyone know why these updates are failing?