I have been attempting to make a rough sketch of a gear to show someone just a little of what I know but I have encountered a situation where a line says that it coincides with the arc of a circle but it isn't connected and so does not count as a closed sketch.

You can see the coincident boxes where it should be attached but the rectangle is not shaded grey. Here is an up close view of the supposed coincident

Does anyone know why this is happening?

(EDIT)

The answer given below is correct and fixed the issue

Message was edited by: Collin Lohmann