Adding a Utilization Validation Rule and followed all the steps and checked applied the challenge on the App and it works fine without any error. But my problem is that when i click Verify Steps i get following error message because of which I am not able to complete my challenge and proceed further. Thank you in advance!

 

Battle Station Trailhead -Step 4:Ad business logic
"Step Not yet complete... here's what's wrong: 
The validation rule does not appear to have the correct error formula. Make sure Exhaust Port Inspectors have > 150% utilization' 
Note: you may run into errors if you've skipped previous steps"