Prevent Save if Cells in a range are still Red (Conditional formatting)

I am having no luck with this. I want to prevent a user from saving the workbook if some cells in Range("K8:S51") are still red because the conditions have not been met to turn change them. Here is what I have thus far and no matter what I do it gives me an error. I am not sure if I use Index number or RGB?

Option Explicit
    
Private Sub Workbook_BeforeSave(ByVal SaveAsUI As Boolean, Cancel As Boolean)


With Sheets("WorkSheet-1").Range("K8:S51")
    .FormatConditions
    If .Interior.ColorIndex = 36 Then
    Cancel = True
    End If
End With


MsgBox "Worksheet needs to be completed properly"

End Sub