Help please, we had a chemical damp course put in 2 years ago and we keep getting a crack appearing about the level they knocked off the original plaster. The crack runs all around the downstairs walls they did. The damp course was not injected but brushed on?? any help or advice would be greatly appreciated. We've repaired the cracks at least 2 times and they still show up. We even had 2 wall's re skimmed with skrim tape over them and they still show up!!!