I think I have run into this problem before, and 2 hrs on the horn with Crystal support finally gained me the following info:
In file -> options, BEFORE you create a report, you have to choose how you want to format numbers (file -> options -> fields -> number -> number). You cannot change the way they'll display once the report is created (hard to believe, but this is straight from tech support's mouth). Now, I have found that you CAN indeed change how they'll display if the field contains a number _only_ (so your field with strings and the "-" won't work like this) and you choose 'format field - ...'.
Sorry to ramble, but I believe if you want to keep your formula as is, you may have to recreate the report once you launch Crystal and set the options as described above. I may be wrong here, and I am sure I will be set straight by someone with more experience if I am, but this was the method I was told to use by CrystalsDecisions support staff.
Hope this helps! -rodbac