charging not supported by this accessory

I've had my 3gs for about 1 1/2 years and I've not had a problem like this before. I got a Sony brand docking station @ Christmas for my son's ipod touch. We both use it, me for my phone and him for his ipod. Well about 1-2 weeks ago I noticed that my phone would say "charging not supported by this accessory". But I've used this dock station since December.... I thought it was b/c I'd not upgraded to the latest software, so last night I upgraded to the 6.1.3.... nothing still. Could it be something wrong with my phone? Or the station? My phone will charge on a wall/USB charger. And my son's ipod touch will still charge on the station, and so will my husband's 1st gen ipod touch. I'd hate for it to be something wrong with my phone b/c it's way outta warranty....