Thank you for responding, however, I don't think that this will do. The problem is that the user inputs two variables for calculation by means of a check box and then after selecting these two things goes on to enter in anywhere from 12 to 56 different measurments. So I have figured out how to average the measurements but have not yet found a way to display a message on this average box everytime it does a calculation. I have looked in the help files and it basically says that you can't use an AfterUpdate procedure on a calculated control. I was wondering if maybe there was a way to getting text box "a" to equal text box "b" and then maybe write the code for the error message.