compelled to select the corresponding dependent drop down list before moving forward

[Vilas Desai]

I have a drop down list in col D and a dependent drop down list in Col E. Based on what is selected in col D AND in col E, I write a formula which is stored in the corresponding cell in Col F. When I select a new value in Col D, I must be compelled to make the appropriate dependent selection in col E, otherwise the formula evaluated in col F takes the new value of Col D and the OLD value of Col E. for ex, f5=(d5 & e5) I prefer to have a formula based solution unless it is possible only through VBA.