Are you sure you have them set up correctly ? as .co.uk nameservers are a little querky' to set up.
They should be come nameservers 'instantly' but you will still need to wait for propergation, upto 72 hours [very slow hours].
I'm sure if you post a little more info, the experts here will comment.
_____________________________________________________________ - There are many types of Marmalade -
Do you actually have name servers running on the other end of those name server host names?
Internic is still showing "No match for nameserver".
I am wondering if this is an issue with 123-Reg. I used the control panel to make a nameserver change three days ago but its still not gone through. There is no point contacting 123-reg support because when they eventually come to the support ticket after several days, I'll get a stupid answer off them.
The website being run from the name servers is actually working so they must be resolving for it to load up, its just other domains are refusing to use those name servers because it thinks they don't exist.
I'm going to switch the domain over to UKReg, I'm sick of waiting for a reply off 123-Reg. At least UKReg reply within about 5 minutes.