Sending typed DataTable results in error

[Cyr1dian]

Hi all,

Situation:
----------
1) I have a typed dataset (generated with the supplied VS tools)
containing several tables (some of which quite large).
2) I have a webservices that needs to expose each tabel individually
3) Exposing the dataset as a whole is not a problem
4) A singleton is used to establish an update queue so users dont get in
eachothers; I don't think this is of any consequence here.
Problem:
--------
In point 2 I try to run the following code (which fails immediately when
running the service, compiling is not a problem)

//snippet

[WebMethod]
public dsPS.tbl_ArticlesDataTable GetArticles(int UserID, int TableIndex,
DateTime LastUpdate)
{
Synchro SyncLock = Synchro.Instance;
if(SyncLock.RefreshLock(UserID)==0)
{
dsPS.tbl_ArticlesDataTable Articles = new dsPS.tbl_ArticlesDataTable();
daArticles2.Fill(Articles);
Articles=(dsPS.tbl_ArticlesDataTable)RemoveOldData (Articles,TableIndex,LastUpdate);
return Articles;
}
return null;
}

//end snippet

This results in the following error

//error

You must implement the Add(System.Object) method on
JNS_Service.dsPS+tbl_ArticlesDataTable because it inherits from
IEnumerable.

//end error
Question:
---------
How do I fix this?
The following I have already tried:
1) Making the tbl_ArticlesDataTable class explicitly serializable in the
generated dataset class
=> Same error
2) Changing output to an untyped dataset
=> Different (vague) error

I have already found many answers/solutions to this particulair error
message but most just explain the cause of the problem withour a
work-around (does me little good) and others describe work-around that
don't seem to apply to my particulair situation.
Thank you for any help,
Cyr1dian