it won't  get dark enough?  UGH!!! Help!!!

AIt's easier to airbrush a cake if you want dark navy blue. If you don't have an airbrush, there's canned colour sprays by Wilton and PME I think?

It's difficult to get enough colour into fondant without it being too soft, although it helps to colour the fondant the day before you new it and rest it overnight.

What kind of icing? Fondant? Buttercream?

Add a bit black to it...Here's a navy blue cake I did a while back.

MMhassa2,    I really like that color. What brand of coloring did you use? Did you use Wilton royal blue coloring paste and add black to the buttercream?  Looks great!!  I would have never thought to add a little bit of black. Thanks for the tip!!

Use Americolor Navy Blue but it wasnt turning into a real navy blue but once I started adding a bit of black I was able to match the birhday girls dress shade :)

Airbrushing is the best as it is a touch not a full infusion of blue/black.

Unpleasant but true side effect, your poop will turn green if too much navy blue icing is consumed.  Don't ask how I know….

When I use americolor navy blue, I always have to a drop of regal purple to get it to go to navy. 

Buttercream

My fondant turned a great navy blue

Thank You all for your help!!!