If you are sending us your files electronically - PLEASE FOLLOW THE INSTRUCTIONS TO INCLUDE YOUR FONTS
There are links below to assist you in correctly embeding your fonts with your artwork/layout

Chances are the fonts may be embedded, but Illustrator may report them as missing (if they are not on the local machine). If you are having problems suppling the fonts, you have another option:

Helpful articles on Font-Embeding:

Font Embedding: Adobe Illustrator

Using Illustrator’s Save As command, you can save the entire ad document as an EPS file.

EPS files must include all fonts used in the document. Illustrator's EPS format dialog box

Use the Type > Find Font to create a list of all the fonts in your file. This allows you to search for and replace the fonts (including the font’s type style) by name. This command also lets you save the list of fonts as a separate file, which can be useful when gathering fonts for submitting with your ad. Illustrator's Find Font dialog box

Note: We request that you do not use Illustrator’s Type > Create Outlines function. It takes longer to print, produces substandard looking text and makes the document uneditable.

For more information on Adobe Illustrator, visit Adobe.com