Hi Everyone... Well I'm having a problem with my backfills. I just did a clients backfills last night and for the first time I had a clear line where the smile line was before. I've heard of this but it had never happened to me. I drilled the smile line out and then filled it with white again but when i filed and buffed the line came out. I went back and added more prduct but it was still there. What went wrong? Please help!!! Thank you guys.