My cookies were looking real nice, but when they dried completely several of them have darker areas...as if they are completely dry in some areas and not others, but they are totally dry. I even tried blow drying one and nothing!

Any suggestions, tips, advice?

It's a problem that has been asked on CC by members in the past. It could be a number of issues...

http://cakecentral.com/cake-decorating-ftopict-555543-patches.html
http://www.cakecentral.com/cake-decorating-ftopict-20383-patches.html



1) did you use a large amount of food colouring? Dark colour? Too much and it can crystallize/have dark patches.

2) did you use too much water to thin out the icing? A high concentration/ratio of water/colouring can also cause this.

3) did you allow the icing to mix properly, esp. after thinning it with water?

4) is the area where the cookies are drying humid?

5) did a drop of oil/butter/fats get into your icing while it mixed? Were your paddle/bowl/piping bags/tips completely clean and oil-free before you began?