I think he means the submit button is disabled because some field failed validation. It might have turned red or have a message appeared next to it - and it might be scrolled off the screen so you have no idea. Or just the common "I have read and agree to ..." checkbox you didn't tick. Possibly because you didn't read the T&C or because it won't let you tick it until you click the link to the T&C. Nobody else read them either but they've learned through trial and error that when the checkbox doesn't work, you have to click the link to fool the computer into thinking you read it.