Data Validation in Excel 2007

[jguillen]

I use Excel 2007, windows XP
Question about data validation, I have data validation in 3 cells and it works well but I have a problem. One is validated from a list the next one is an indirect relation to the impute of the first second just check to make sure both first and second cell have an entry.
If the user enters the correct entries and goes back to one of the imputed cells and changes any of the values in the cells that are not a valid entry, it allows the change.
How can I correct this?


Here is a short version of the workbook.