First of all, I would read the package insert very carefully. I do not know this particular reagent, but I do know that sometimes panel cells, depending on what they are suspended in and their concentration, just are not suitable for use as controls with some reagents. Secondly, a Ee cell had been chosen to test the antiserum. Some of the posts above were worried that this cell might have been used to rule out an anti-e. Well, I hope nobody is using Ee cells to rule out the presence of anti-e with ee cells being in such abundance. Thirdly, you have probably got a second lot of panel cells. You should test the anti-e with the Ee cell on the other panel. If that is reacting strongly, then it is possible that the original Ee cell was in fact a previously undetected RH:CE variant and the manufacturer should be notified. That should not stop you using the cell, however, as you would look at the panel results as a whole, and not just this cell in isolation, and the other antigens (outside the Rh system) would not be affected. On the other hand, if none of your Ee cells are reacting and you are following the instructions in the package insert to the letter, then you probably do have a problem with you anti-e. You should stop using it and contact the manufacturer. They may well need examples of the cells that you are finding negative to see if they can reproduce your reactions on their retained samples.