Problem with UK Whois edits

[Colin Viebrock]

Occaisionally, when trying to edit the whois for a .UK domain, the API 
returns the following message:

(
    [response_code] => 437
    [response_text] => A request is currently waiting on this domain.
)
What does that actually mean?

- Colin

p.s. sorry if this is a duplicate message ... I thought I had sent it 
already, but it never came through on the list.