A question mark (?) appears in the Price Sampler.
If a question mark appears in the Price Sampler, this indicates that there is an error in either the Set Price field or the Formula field which calculates the markup.
Check both the Formula, to see if a ? also appears in the Markup field, and the Set Price, to see if a ? appears in tan field (not the off white box where the equation is entered).
Once you know which field is causing the error, you can then correct it.
If you have difficulty locating the error contact tech support for assistance.