Photoshop line tool not working

[simms32]

My photoshop line/shape tool has a tiny cross in a circle next to the cross hair and subsequently won't work. I've checked layers are not locked (even though it's a shape) but all to no avail. can anyone please advise? Thanks

[CADTutor]

Is there a current selection? Enter Ctrl+D and then try the line tool again.

Another thought - are you in quick mask mode?

[Fritz]

If your using a dark color (like black) is your layer mode set to screen? Or conversely, if you're trying to make a white line, is your layer mode set to multiply? In either of these cases your line will not appear because screen only shows light colors, and multiply only shows dark. Some of the other layer modes can effect what you see in similar ways. Make sure that's set to "normal". Also make sure your layer is on, and you're not in a mask.