When building a TextBox or Label UserControl, the Caption or Text property sometimes doesn’t work well with the standard controls, as the control’s appearance doesn’t change when you type the value into the Properties window.
To make your UserControl behave the way you want, go to the UserControl’s code window and select Procedure Attributes from the Tools menu. Find your Caption or Text property on the combo box and click on Advanced. On the Procedure ID combo box, select Text. Test it by putting an instance of your control on a form and changing the Text or Caption property at design time. The Property Let procedure will fire with each keystroke, allowing your update routine to reflect what the user has typed.