We have used yeast dropout plated for more than 10 years using same catalog number of Difco Agar (214520). Somehow from last summer our yeast genetic experiment was not working well. We struggled so much. Finally we addressed agar. It looks not working for dropout plates. We concerned the specific batch thus we ordered same agar new small one. Still they are not working. I attach the picture of our test. We borrowed old other cat number of agar (BD214010) from other lab. It looks like working. I attach the picture of our testing. If you have any similar issue, please let me know.