No given Value for one or more required parameters

Question

I have a database Oledb. With several textbox and comboboxs. One combobox I have added numbers to selecte from 1,2,3 the Winform works fine but if i change the options to A,B,C I get No value given for one or more required parameter.The oledb / Access file is set to Short text. 

Any idea why this happens?

 

Thanks