Saturn Brake Question (no lbc)

Help Y'all,

Told my daughter that i'd look at her brakes.
'93 Saturn 4-wheel disks no abs.
I can get the caliper off and the pads out, but I can NOT
repress the piston. Thus, can't replace the pads.

Have put it back together as is for now, but I'd sure like
to be able to do this.

Hints anyone? I have opened the bleed screw
and tried using a clamp to depress the piston.
No luck.

Whassup??

chuckc