Data Type Of Items In Controls Collection?

I have a UserForm function which accepts as a string the name of a TextBox control on the form. The function returns a reference to the named TextBox control (or Nothing if the control does not exist). I have the function header defined this way:

Public Function TextBox(byval strName as String) as TextBox

The function returns a reference to the TextBox control like this:

set TextBox = Me.Controls.Item(strName)

(I know, the .Item is not required.)

The code which calls the above function first declares a TextBox object with this Dim statement:

Dim txtTextBox as TextBox

The routine then goes on to call the TextBox function like this:

set txtTextBox = TextBox(strTextBoxName)

When run, the above statement genrates a Type Mismatch error. I'm confused, because if I 'TypeName()' the TextBox function's returned value, it's "TextBox,".

I thought I could work around this problem by changing the TextBox function's return value's data type to Variant, but that produced the same result.

The only "solution" I've come up with is changing the TextBox function's return value's type (and any reference to the functions' return value) to Control.

I expected that the Controls object would behave similar to a Collection object in that it's items can be different types (TextBox, Label, CommandButton, ListBox, etc.) and no Type Mistmatch erros occur so long as the type of the item returned matches the type of the variable referencing that item. But is seems that Controls requires that any reference to one of its items must be type Control, not the actual type of the item returned.

I'd prefer not to use Control data rypes in my applcation, as that would require additional code in all of my subs and functions to ensure that any Control object passed to it is the correct type of control (TextBox, Label, etc.).

Can anyone explain what's going on here? Why shouldn't I be able to assign a TextBox type variable to Controls.Item("xyz"), so long as the item returned by Controls.Item("xyz") is type TextBox?