It seems your lines are single lines. Not connected. For example you can use the Live Paint Tool - this will help you to create closed paths (areas)
You're right, it is single lines... how do you draw with the live paint tool?
I'm only starting to learn Illustrator, but it seems this tool is used to paint different areas of a drawing.
I tried to use the Live Paint Tool on the drawing I'm working on, but it didn't close the gap.
Any other ideas?
Oh that's a great article, thank you, just learned a bunch!!!
But, sadly it didn't fix my problem.
I followed the instructions and it says there is no gap and I believe it's correct.
The inner lines are touching, it's the outer lines that are not.
Not sure if it makes sense or not.
There are two solutions.
The first is to make the tip shape of the line round.
The second is connecting the lines.
Use the direct selection tool to select both ends and connect them.
How cool! It worked!!!
Thank you so much!