Surfing Waves

Ok so heres my problem. I can do the first parts of a cutback fine I can get up the face and get my start carving it around fine but I would say one out of every three times, towards the middle of the carve, the front part of my inside rail starts sort of sinking into the water, and I fall. Is this because I am putting too much weight on my front foot, because I am too far up on the board, or because of some other technique flaw. Any help would be apreciated

power through your turn with your back foot. Keep pressure a minimum on your front foot. Also, look before you turn!

I'm having the exact same problem but I only have it when surfing frontside(I know sounds crazy). I think part of it's a matter of speed, recently I've noticed if you get a bit lower and foreward in a little more until you hit the lip, and then immediately transfer to your back foot when swinging around the front it works a bit better.

recently got over the same problem myself with a little help from some local friendly rippers. they told me i was overestimating the power of the wave and that i wasn't compressing enough at the lip. causing me to dig a rail.
when you have picked your spot at the top of the wave you extend your body. as you hit the top i was forgetting to compress again fully which exagerrated the weight my lean would transfer to the board. a compressed body transfers the weight much more delicately.
after this point with your leading hand and look where you want to go. somewhere back towards the middle of the face behind you. just as the board swings under your hand, continue the same motion back to the white.

Garbarrage, do I just have to compress as I reach the end of the wave nd hold that form while looking over my shoulder? I hate digging a rail, or losing all my speed by doing these cutbacks incorrectly. how do I finish off a cutback with a backside re-entry like pros?

sorry took so long to get back to you mate... don't know how to do it like the pros, when i do it 9 times out of 10 its pretty weak but every so often nail one that feels good.
pretty much just continue the rotation extend a little to help the board rise, and again point and look where you want to go compress at the top and swing the shoulders (point and look again).
digging a rail is part of learning, i still do it quite a bit but happens less and less with time. some sessions more thatn others.

there's a great instructional DVD called 110% surfing techniques. explains everything in detail for a variety of maneouvers. look out for vol. 2 as vol.1 is a little bit basic and pretty much everything is covered in the second one anyway.