Did you join WikiTree? http://www.wikitree.com/wiki/Member_Types
Or are you querying why an ancestor Profile doesn't have lineage all the way to you?
If that is the case, you can looked at your ancestor's Profile, and on the left hand side, under the ancestor details there is a line with the Profile manager's name and a link that looks like [send private message].
If you click on that link, you can email the Profile manager and ask your question and share your information - so that you can determine the connection. You might find a long lost cousin!