Table is read only error with Cached Updates

Hi

Can someone explain what the error 'Table is read only' means in combination
with Cached Updates. I get this error every time I apply the updates on a
simple TQuery. The SQL statement is just select * from table and the SQL
statements in TUpdateSQL are generated by Delphi and are correct.
Only by removing most of the columns in the Where clause of the ModifySQL
statement I can get this to work but then of course users will eventually
overwrite each others data.

A problem related to this is that in in the OnUpdateError event handler i
get only simple EDatabaseError exceptions which contains no useful
information regarding the error, instead of the much better EDBEngineError.

What am I doing wrong?

Martin