Must close or hide topmost modal form first (Error 402)

The modal form you are trying to close or hide isn't on top of the z-order. This error has the following cause and solution:

• Another modal form is higher in the z-order than the modal form you tried to close or hide.

  First use either the Unload statement or the Hide method on any modal form higher in the z-order. A modal form is a form displayed by the Show method, with the style argument set to 1 – vbModal.