Writing To Database/Datatable In Simple Project?

I have created a simple project where I have two forms, one a data entry form where a client name, address, city, state and zip are entered into textboxes. Then, the user clicks a button to add all this data to the datatable via a newrow. The second form includes a datagridview to show the datatable. However, I cannot get the code below to work to update the datatable. I have a button to click to check to see if the data is entered and it returns an error that no row exists.