Combox that contains letters textboxs stop working

I'm working with Form 1 I have 15 textboxes and 2 combo boxes. You can select from the combo box exp: 123, 456 B789. Program works well as long as I dont select B789 has a letter in it. I can change it to 123 or 456 and i can add to any textbox. The Letter has stumped me.

 

In the beginning my dbo.Table was set to Numric for the combobox I have changed it to Varchar but it still dont work.

 

If I try to add to any other textbox with a letter in the combobox  it stops.

 

what else should I be looking at?