Data access error

I have a score form that contains a grid that accepts scores from user ,and then display those scores to another page called playerform.
the problem is that before scoreform opens it just rebuilds the score table that deals with all above task.after that only i can enter scores into the grid.

when i enter score in the grid one by one ,it doesn't allow me to enter scores in the second line of the grid and throws a error.
"data access error.row cant be located for updating"
but when i try to do the same task without rebuilding the scores table,it works perfectly.
any one plz help me out.