[twitter-dev] You aren't allowed to add members to this list

[YARG]

Hi, I'm updating a .net lib so it can handle lists.  List creation is
OK but when I try and assign a member (an account which I also own) to
the newly created list I get the error:

<?xml version="1.0" encoding="UTF-8"?>
<hash>
  <request>/1/twitterapi/team/members.xml?
list_id=7869628&amp;id=94564101</request>
  <error>You aren't allowed to add members to this list</error>
</hash>

I've checked the docs and and I'm pretty sure the Ids are OK.  All
I've found is that you can't add a user who has blocked you to a list
(the member account that I'm trying to add hasn't blocked me as I own
both accounts).

Has anyone any ideas?

Cheers

Steve