populating a datagridview from a 2nd form

I am having trouble populating a datagridview using a 2nd form.

The datagridview is bound to a table on form 1.

There is a button on form 1 which displays form2 where I enter the data to be displayed in the datagridview on form 1.

The first time I do this it works fine and creates a new row in the datagridview and updates the underlying table. The second time thru, it populates the new row but does not create another new row. this row does not update the underlying table.

Does anyone know why