A question mark (?) appears in Set Price field in the Price Codes file.
This indicates that there is an error in your Set Price formula.
The most common error is a decimal after the number. E.g. 2. instead of 2 or 2.00.
Check the price sampler column on the right. If it also shows question marks after clicking on the Reset UI button, then the formula has an error in it.
Take a look at the equation in the Set Price field or contact tech support for assistance.