Autosizing mask cant click center arrows

No doubt an obvious question for those in the know but I'm trying to make my view look nice (ie. expand vertically) on an iPhone 5. To do this I've been told I should have the autosizing mask set in such a way that all items are ticked, including the interior two arrows.

Trouble is on this particular view I can't tick those arrows, it won't let me.

Any ideas?

Here's what the image looks like:

enter image description here

Solution

In interface builder go to the pane on the right hand side of the screen. If you go to the 4th tab from the left:

enter image description here

You will probably see that you have the "Size" set to something other than "Freeform". If you set it to freeform you will then be able to set the "springs" on the view so that it fills it's superview.

Hope this helps.