I don't think it's a fault - recent Blackberries will only charge when something that they recognise as a genuine BB charger is plugged it. I've assumed that they put something on the data lines of the USB connection that tells the BB to charge (but don't quote me on that - this is pure guesswork on my part!). The USB chargers that standard on Blackberries in the UK come with Euro and US plugs on them, so one of those sounds like it would do. The part number is ASY-07559-001, if that helps.
In a similar way, if you plug a BB into a random PC that's never had BB drivers loaded (e.g. one not running Windows) it won't charge either.