So I'm trying to come up with a percentage for two colums of data within my report.  I have an picked and return columns and I want to do a percent of what is being returned and then sort by the percent.  I have some totals with zero so when I enter the return/issue*100 it errors because of a divsion by zero.  So I coded around that, but it will not let me us the percent as one of my sorting options.  Here is the current forumla I'm using:

Another trick is if you can insert another summarization that gives you the correct data for the order you are looking to achieve and then use the formula to display the data you want to show the end user.