Divide tool not working

I find the Shape Builder Tool to be much more intuitive than Pathfinder. You might try using it to divide your shape. Select all the parts with the Selection Tool (V). Then select the Shape Builder Tool (Shift + M). Hover over areas that you'd like to become distinct shapes (right now you have concentric circles with lines overlapping at various parts). Click to make a highlighted area a new shape. You can also drag across areas to add to the shape. If you want to remove part of a shape, you can Alt + drag (PC) or Option + drag (Mac) to subtract. Here's more info on the Shape Builder Tool How to create shapes using the Shape Builder tool in Illustrator

One thing I am seeing is that you have a Path selected, and the selection anchor points are on the circle, not a wedge. That's why the circle is getting the fill.

I also see that out of the three lines, one crosses both circles (the bottom one). Two cross one circle and go only halfway into the next.

Open your layers panel to see what you have, and post a screen shot if you want to.

Be sure you select all objects when you use Pathfinder > Divide.

Or, alternatively, use Live Paint. Select all objects first.

Select all and use live paint.

Read the introductory pages of the documentation, so that you know how vector graphic works.