Curves Question

When I attempt to put the input and output when in curves, I can only go up to 98 and as low as 2.
No matter how many times I click on the line or what position it is in, I cannot enter anything above 98 or below 2.
I use Photoshop 7.0 --what am I doing wrong?

Thanks in advance!

Edit: Problem solved! Thanks strangelittlex :)