Formula to include spaces in linked data validation list

Hi
I have a spreadsheet with 2 linked data validation comboboxes. A ws_change function runs depending on the selection from cbo2 ,to populate a named range table.(I've attached a simplified example with further info)
In cbo2, I've used the INDIRECT feature with a substitute formula to replace the underscores from the named range in cbo1.
However, the selection for cbo2 has spaces ie Dept 1a (can be replaced with underscores if necessary) so to enable the ws_change to run, I have to delete the spaces, ie Debt1a
Is there a way to include the spaces in List 2? I've tried a nested substitute formula but with no success.

Any assistance will be greatly appreciated
I am trying to teach myself excel/vba so apologies for any incorrect terminology
regards