why When I use ADO's cn.BeginTrans,error: can't begintrans with firehose?

my email: [email protected]

if I understand the documentation correctly, a firehose cursor is a read-only cursor.
Thus transactions don't make sense, do they?

but sometimes the error appear,sometimes it doesn't appear,why?
on error goto dberr
cn.BeginTrans 'Expression is right,but execute it is error
...
cn.commitTrans