When I setup the PopulationDataSourceSettings on a combo box, I am trying to use a FillAll function which return the count of records in the BO after the fill.  I dont care about the return value when filling the combo, but I still want to use the FillAll function to fill it.  However, it's not available in the Method to Execute dropdown unless it's a Sub.  Is there anything that can be done about this or some reason it is like this that I'm not understanding?

Well, it did have a return value as a Function...functions are required to have return values, but in this instance I don't always need to use the return value.  I do have it working as a Sub, but I would really like to be able to use Functions in here as well.  I may have a FillAll that I would like to sometimes use and get back the count which I want to use in a dropdown.  I can't use it there as it is right now.

In C# that is true 100% of the time.  It sounds like you have your project setup correctly, but it is actually possible to omit this in VB....and then problems will occur.  The other thing that you can do in VB.NET, which is frustrating, is omit a return statement since by default is has a reference value to itself for backward compatability....wish you could force BOTH of these things to a compiler error no matter what!