copyscape is it picking up everything!!

The title sounds like a noob question but let me explain for as long as I can remember I have always put content into copyscape if it passed I was good to go.

Recently on a site that I have had little results from a campaign i just ran i decided to do a little digging.
My first port of call was to check if my first tiers were unique (some of my competitors in this niche try and attack on all fronts)

so went to some of the web 2.0's copied the content and nothing came up not even the original article on the web 2.0.
checked this for several web 2.0's and it was the same. Went over to google checked content is indexed and cached also when you search sentences from the articles google finds it. These articles were written by me and aren't encoded or anything like that.

my question is why doesn't copyscape find it makes no sense to me at all.

copyscape might not have crawled yet them

it is not google and doesnt have such resources

You should try and recheck it in a few days time but usually for me, if Google has indexed them, Copyscape should be able to detect them.