Excel - VLookUp
1 - The online help file regarding Vlookup does not specify that the matching values in the range must be sorted in ascending order. All of the examples show the data sorted in ascending order, but the directions do not specify that.
2 - Do you have normal users try to follow the published directions for the use of MS Programs, formulas, etc? This would be an excellent way to determine if your examples and directions are good. Normally, I find solutions outside of MS help files because they quite often are too confusing. I have an MBA and have a pretty good understanding of MS Office.