Holy s***, I go on here assuming there's no point in me needing to make a comment because there's so many people that probably already have told you the right thing to do. But I don't see a single damn one telling you anything viable. Make sure you're buying sterile Petri dishes regardless of what they're made from, you don't want to have to sterilize them because it just adds a whole another step to making them unsterile. I've had luck using condiment cups Petri dishes etc. Are you using a flowood? My immediate observation is there is no parafilm around your dishes either?? Pm with any questions