Nice job on the Mustang. I love the color.
As far as the glue goes I'd say that the tip is plugged or your glue is old an dried up completely. Take the top off and see if there is fresh glue in the bottle. If there is then your tip is plugged with dried glue. You may need to get a new tip or a new bottle of glue.
Too, you might want to add liquid cement and CA glue to your arsenal.
Later-