droid with Red triangle in recovery

hey guys,
I am noob to rooting. rooted my nexus s GT-I9020 recently and installed clockworkmod recovery 5(worked finely when installed). tried installing slim bean, installed rom manager also. flashing recovery was un successful and when tried accessing recovery and found [Only registered and activated users can see links. Click Here To Register...] the droid symbol with a red triangle in its stomach!!!! I am not sure where i messed it! Kindly help me please. Many thanks!!!