Even though Closed, one note to help others, the issue occurs because of the format
Boolean = True/False ( A logical Check for the Truth Value)
In your case your code is looking for a boolean, because that is the standard for that setup
So
ComboBox7.Text = ComboBox8.Text = True ('Or False)
If you (not that this would work for you) set combobox9.value as a boolean
Dim BL as Boolean = Combobox9.value
then the code wouldn't error, though it wouldn't work for your purposes.