You have an event which expects zero arguments.
You are trying to add a handler method which expects one argument - a
Event handlers MUST
match the signature of the event they handle. If they don't, you get the compiler error shown in your screen-shot.
You have declared that
an event handler method which will accept two arguments -
sender As Object
args As ComboBox.ObjectCollection
The method does no such thing.
Since the method doesn't return anything, VB "helpfully" inserts a
before the function exits. If you try to use the return value, you will get a
You need to start again, and read a few tutorials on how events work.
Events (Visual Basic)
Raising Events and Responding to Events
Walkthrough: Declaring and Raising Events (Visual Basic)
Step by Step: Event handling in VB.NET