I jailbroke my ipad 3g 4.21 with Greepoison RC5 and it has been working great.

I didn't have a SIM card in the iPad when I jailbroke it but now I want to use it on 3g as well as wifi. I put a new SIM card in today and I get "no carrier"

I have tried resetting the network connections and power cycling the device but still have no luck.

I have spent ages looking around the web for ideas but no luck.

I am running IOS4.21.

Any ideas?