When you give the evidence to Greg, he puts a small tag on it. At first the evidence will appear with a grey tag- that means the evidence has not been analyzed. If you have analyzed everything to do with it, the tag will have a red dot on it. If there is something left to do with the evidence, the tag will have a yellow dot on it. [Of course if a piece of evidence does not have a tag on it, it means you haven't given it to Greg yet
] The tag looks like a regular price tag a piece of clothing at a store would have.
Make sure that all your evidence has the small tag on it. If you have any evidence that is grey or yellow tagged, that means that there is something left to do with it [in the lab, or finding a match for it in terms of DNA, etc.] Does that help?