Hi Jean,
I have never try the B1Studio with VB.
In C#, once we add the EditText in B1Studio, I would highlight the EditText and go to the properties.
Under this property, there should be events listed. On the 'BeforeValidate' event, type in a name, it should give you a procedure to handle this event.
If above does not work with VB, understanding how VB works, after you add the EditText,
Go to your code.
Under the selection of objects combobox on top, select your EditText, under the EventHandler selection, select BeforeValidate event. VB should auto create the procedure for you.
Regards
Edy