DIAGNOSIS This is almost always an issue with the seal, or you're just not getting enough heat into it yet. The gauge reads internal pressure, while the regulator rocks on steam flow. If they're not matching, the lid isn't sealed tight.
FIX Turn off the heat and let it depressurize completely. Unlock and lift the lid. Check that the silicone sealing gasket is seated perfectly in its groove all the way around—no twists or gaps. Clean any debris off the sealing surfaces. Close it back up, make sure the lid handle aligns directly over the base handle, and lock it down firmly. Start over with high heat until a steady stream of steam comes out the vent pipe, then time your 10 minutes of venting before putting the regulator on.
IF THAT DIDN'T WORK If it's still not sealing, the gasket itself might be old and hardened. On the Presto 01755, the gasket is a replaceable part that can lose its pliability over time, especially if it's stored compressed in the lid. A new sealing gasket usually solves a persistent no-pressure issue.
HEADS UP Never force the lid open or closed if there's any pressure left. The locking lugs are aluminum and can bend. Always wait for the gauge to read zero and for the air vent/cover lock to drop down completely before unlocking.