try it on a smaller curb if it is too high, if isn't that, try to Keep your shoulders parallel at the curb when you pop your ollie

And don't only try to put your skateboard on the ledge, just pop your ollie and you'll be right on it !

Try to keep your back foot on the tail and catch some speed

Learn how to ollie higher and try again

You need just to do it. Just hop in it

Higher ollie

Ollie bigger

Ride up to any thing you are trying to grind on and Ollie as high as you can