Lists.asmx item person not in UserGroup.asmx GetAllUserCollectionFromWeb method

Question

I am using Lists.asmx's GetListItems method, then I'm using info from UserGroup.asmx's GetAllUserCollectionFromWeb method to get more user details about a person in one of the columns of the list.

I was alarmed to find that many of the items I get from GetListItems have a person that is not listed in the result of calling GetAllUserCollectionFromWeb.

Why would this happen and how do I fix it, or should I be using something other than GetAllUserCollectionFromWeb as a definitive list of all people who might be stored in a person column of that list?

Answer 1

Rather than call GetAllUserCollectionFromWeb, get the list items for "UserInfo":

GetListItems("UserInfo", null, null, null, "100000", null, null);