The problem was probably that Wilton does not make luster dust. Their product is shimmer dust which is completley a different thing. The shimmer dust is made to be sprinkled and will just gum up if mixed with a liquid.
Edited to add that I am really looking forward to ordering some CC luster dust, just waiting for them to roll out the colors I use most! 
Yeah but the thing w/ Luster Dust is you can't eat it - and even though Wilton's shimmer dust may not be as vibrant as the Luster dust atleast you can eat it....so if you're just wanting to use something for decoration the Luster is the best but if you want to eat the cake then use the shimmer. That is what I was told so please anyone correct me if I'm wrong and Luster Dust can be consumed.
There are already some threads about the use of luster dust around the site.
The basic message is : In the UK it is considered ok to consume luster dust, in the US, the FDA has not approved it as a food product, but it is non-toxic, and ingesting small quantities of luster dust will not harm you, it passes through your system.
Legally we cant call it a food product, and we have to put FOR DECORATIVE USE ONLY on the jar since it is not a Food Product, but you can ask around the community for common sense uses of Luster, Pearl, Petal, Sparkle dusts.
Yes well I understand some people may go ahead & eat it but if a person purchases a cake w/ Luster Dust all over it & eats it and then asks "Oh what is that stuff" and you tell them Luster Dust and then they later find out it's not FDA approved then they may be unhappy. I have never used LD & if I do (which I'm sure I will someday I will only use it on accenetd pieces that are only meant for decoartion & I won't put it all over the cake) If I want something for all over the cake I'll definitly go w/ Wiltons Shimmer Dust.
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