Which device are you using Animate on? What's the OS and version on your device?
Try to connect the lines in order, one after another. This worked for me.
Few things to check..
- Ensure that all the shapes are present on the same layer.
- Check if the shapes have been drawn in Object mode. You'll have to break them apart if that is the case.
- Zoom in and check there are no open gaps in your shape.