How to disable editing in the existing rows in a datagridview and allow the user to add new row to same?

Hello,

I have a datagridview where I should not be able to edit the the existing rows, but i must be able to add new rows to it.

I have set the datagridview.ReadOnly=True (for disabling edit)

Also to allow the user to add new rows, i have set as  datagridview.AllowUserToAddNewRows=True

But the desired effect is not happening. Still I am not able to add new row.

Can anyone help me in solving this problem?

Thanks in advance.