Making conductive traces for capacitive touchscreens
First, is your pen well-shaken, so the ink is silver-laden?

If not, the ink may be barely conductive.  The ink will settle out to form a silver clot inside the pen, and the your circuit-lines are mostly the solvent, not the silver.  These pens contain weighted beads to stir up the silver and distribute it in the ink.  (Like the metal beads inside an aerosol paint can.)  Always shake up the pen for minutes until the beads come loose, so they 'clack' back and forth inside between the ends of the pen.  I do this by thumping the front and back of the pen alternately against a solid surface (with tip-cover on, of course,) then shaking for 30sec once the beads are making a sound.

Besides too-sparse silver, I would suspect a bad connection between the metal (aluminum?) shaft and the silver ink.  Aluminum foil won't help this.   Instead, clean off most oxide by scraping/sanding a 1cm region of the metal that's next to the plastic.  Coat it heavily with silver ink.  When dry, position a thick ink-droplet at the joint between the ink-coated shaft and each ink-trail you've painted on the plastic.

To make thicker coatings, you can unscrew Circuitwriter pens, tilt, and use the back of the pen as an inkwell with toothpick or tiny paintbrush.  Or, after shaking to mix the ink, unscrew the pen and just dip your tiny brush in the ink-blob found in the back of the white tip section.   The blue body unscrews from the white tip.  Note that the threads of the pen are backwards!  With the pen pointed up, turn the white tip CW, not CCW.

Finally, if your pen is old, the solvent escapes, the ink thickens and won't flow.  (Open the pen and find that the ink stays put, like paste.)  Thin it with a small amount of common spray-paint solvent, xylene.