Excel VBA - Run-Time Error '424': Object Required - vba

Question

I have the following code for a Check Box (ActiveX Control) using Excel 2013:
Private Sub CheckBox1_Click()
If CheckBox1.Value = True Then
CheckBox2.Value = False
Else
CheckBox2.Value = True
End If
End Sub
Private Sub CheckBox2_Click()
If CheckBox2.Value = True Then
CheckBox1.Value = False
Else
CheckBox1.Value = True
End If
End Sub
What it does is simply uncheck Box 2 if I check Box 1, and vice versa. But if I use the above code for a Check Box (Form Control), I get a "Run-time error '424': Object required" error message. Does anyone know of a solution?
UPDATE: The same code above that I tried using in a file that I got from Bytes somehow worked. Since I'm a newbie in VBA, I think I'm gonna have to sit down and study how Excel, Macros & VBA work together. Once I find out the source of the problem (that technically I created myself), I'll post an answer here as to how I figured it out. Thanks to everyone that posted comments & replies. I really appreciate it!

Answer 1

There's a UX (user experience) issue here.
Checkboxes are for when you need the user to pick one or more values.
OptionButtons are for when you need the user to pick one of many mutually exclusive values.
So what you need is OptionButtons (ActiveX controls) - make sure they have the same GroupName, and you'll get the exact same behavior you're trying to achieve, without writing a single line of code:
And then in your VBA code you can access them all by their name (e.g. OptionButton1) to verify their value.
Form controls vs ActiveX controls
"Form Controls" are just shapes that you can assign to a macro (e.g. do something when the user clicks it) - you can't access them and their properties in code like you would with ActiveX controls.
With ActiveX controls you can access them as if they were global object variables, and do what you did:
CheckBox2.Value = True
The biggest hint you get, is IntelliSense: with ActiveX controls, when you type the dot (.) after the control's name, you get a dropdown in the editor, telling you that the VBE understands what you're talking about; when you do the same with a "form control", you don't get that dropdown, and the VBE does NOT understand what you're talking about - and if you persist and run that code, you'll run into run-time errors like you did.

Answer 2

You refer to a Form control by name or index into the Checkboxes collection:
Activesheet.CheckBoxes(1).Value
for example.

Answer 3

You use the incorrect Event listener. Try this
Private Sub CheckBox1_Change()
If CheckBox1 = True Then
CheckBox2 = False
Else
CheckBox2 = True
End If
End Sub
Here is the list event listeners for checkbox