What version? ALWAYS tell us the version you are using. We cannot help you if we don’t know what tools you have available.
How did you create the shadow? What settings? What is the shadow appearing on? Include a screen grab showing the shadow and the settings used in the Drop Shadow dialogue.
As Scott said - more info. The disappearnce of the shadow could simply depend on you using a PDF profile that doesn't support transparencies and requiring manual flattening of the artwork. The same applies to specific combinations of blending options, clipping masks etc.
Thanks for your reply Scott. I'm using CS4. I created the shadow from Effect
Stylize > Drop Shadow...
and added a 50% shadow. Multiply mode, color = black, X offset: 0.1 in, Y
offset: 0.1 in, blur 0.07 in.
The shadow I added is to an outlined skyline. I'm attaching the Shadow as it
appears in Illustrator.
I grouped all boxes on my layout before saving as PDF - could that have
anything to do with the shadow
disappearing? Also, the shadow appears on everywhere I've used it on the
layout except for the skyline.
Thank you in advance for your help!