The shot-stopper is in the final month of his loan spell and would have penned a deal until the summer were it not for snowy conditions last week.
Walker has been a key figure for the Us since his move and he is still desperate to get a longer deal finalised.
He told Colchester's official website: "I was more than happy to sign but because of the weather I couldn't get in, I tried to do it on my fax but my technical knowledge is not very good and I thought it had all gone through.
"I'm not sure what's happening to be honest, but as far as I am concerned I am happy to stay for the rest of the season.
"I am just hoping they can sort it out and I can stay until the end of the season because I think we have started something really good here."