Open the bleeder and try again, you may just have too much back pressure. Make sure the cap is off the master cylinder, they can seal tight enough to prevent moving the piston back.
Also, I think you have a floating type caliper -- piston only on one side on the front brakes.
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!