ODBC3, VB, cursortype, bug and transactions

I installed ODBC3. After some tests I have some questions: (excuse my poor english)

With this code:

Set rstCustomers = New ADODB.Recordset
rstCustomers.CursorType = adOpenKeyset
rstCustomers.LockType = adLockOptimistic
rstCustomers.Open "SELECT * FROM customers", cnnGPro

rstCustomers.AddNew
rstCustomers.Fields("name").Value = "Joe"
rstCustomers.Fields("age").Value = 20
rstCustomers.Update

nID = rstCustomers.Fields("id_customer").Value

I can get my id_customer, but if I change the cursor type to adOpenDynamic, I won't get.

I think that I found a bug:

Set rstCustomers = New ADODB.Recordset
rstCustomers.CursorType = adOpenKeyset
rstCustomers.LockType = adLockOptimistic

cnnGPro.BeginTrans

rstCustomers.Open "SELECT * FROM customer WHERE substr(upper(name), 1, 1) = 'M'", cnnGPro

Debug.Print rstCustomers.RecordCount

Do While Not rstCustomers.EOF
rstCustomers.Delete
rstCustomers.MoveNext
Debug.Print rstCustomers.RecordCount
Loop

rstCustomers.Close

cnnGPro.RollbackTrans

After I deleted the last record I get a error (80040e23) at rstCustomers.MoveNext.
Prior after the last delete I get:

? rstCustomers.EOF, rstCustomers.BOF
False False

After the error at rstCustomers.MoveNext, I get:

? rstCustomers.EOF, rstCustomers.BOF
True False

If I change the cursor type to adOpenDynamic no error will happen.
So if I need my id_customer I have to use adOpenKeyset and if I need to delete a record I have to use adOpenDynamic.

More one, how can I know if a transaction is serializable?
I tried

cnnGPro.Execute "SET SESSION CHARACTERISTICS AS TRANSACTION ISOLATION LEVEL SERIALIZABLE", , adCmdText + adExecuteNoRecords
cnnGPro.Execute "SET TRANSACTION ISOLATION LEVEL SERIALIZABLE", , adCmdText
cnnGPro.IsolationLevel = adXactSerializable

but this last one fail when I did a begintrans.
Where can I confirm that this isolation is active?

Last,

cnnGPro.Execute "BEGIN TRANSACTION", , adCmdText
cnnGPro.Execute "COMMIT TRANSACTION", , adCmdText
cnnGPro.Execute "ROLLBACK TRANSACTION", , adCmdText

doesn't work.

Marcelo Cid