Updates to table through enterprise manager roll back without warning

[Mark Neilson]

I have a table with a trigger on it that includes a cursor to iterate
through the inserted rows

I can get a stored proc to make the trigger logic work
but any updates through enterprise manager - table - show all rows roll back
without any warning. Same behaviour in ms access

Setting a trace on the table doesn't give me the information as to why it is
rolling back. The cursor is being opened and fetched into with
sp_cursorfetch

Is there a way of stepping through the trigger when doing updates in EM
directly?