The error message tells you that you need at least one instance of the object type in at least one layout of the project.
So you're probably trying, on some collision, to create some sprite without this original instance, causing the issue.
Create one instance of the object type somewhere in your project it should fix the issue.
Also, moving this topic, since it has nothing to do with scirra's website. C2 help requests are to be posted in either "Construct 2 general" or "How do I" forums.
Also consider providing a capx to make it easier to investigate the issues.