images as button couldnt post data!!

i use an image as the button of a register form, but when i click the form, it doesnt post the data into databse....why?

Did you use input type=image?

<input type="image" src="/images/send.gif" alt="Send">

no...... i not familiar with this technique...... what is alt = "Send"??

ok....it work alr....thank you!! what is the meaning for this alt ="send"????

If your browser can't find the image then it displays the value in the alt (alternative) attribute instead.

And in some browsers, that text displays as a tooltip.