I am trying to make it so when cell F15 (which has a list data validation) is set to "Off", that checkboxes 19, 20 and 21 are disabled. When F15 is on anything else, the boxes are enabled. My code is below.

It disables it always, regardless of the value.

I have a feeling it is what i named my sub as, but I am relatively new to VBA and cannot find how to appropriately name it. Any help would be appreciated. Thanks!

Code:
Sub Worksheet_Activate()
If (Sheets("Generator").Range("F15").Value = "Off") Then
Sheets("Generator").CheckBoxes("Check Box 19").Enabled = False
Sheets("Generator").CheckBoxes("Check Box 20").Enabled = False
Sheets("Generator").CheckBoxes("Check Box 21").Enabled = False
Else
Sheets("Generator").CheckBoxes("Check Box 19").Enabled = True
Sheets("Generator").CheckBoxes("Check Box 20").Enabled = True
Sheets("Generator").CheckBoxes("Check Box 21").Enabled = True
End If
End Sub