When I hold down the button 1/2 way to auto focus there is a squeking noise and it never takes the picture. It just stopped working, has worked prior to this. It will still take pictures in manual focus, but I'm trying to take pictures of a moving 1 year old little boy, and manual focus just doesn't work for me.

Try pressing the button down all the way quickly. If that doesn't work just play with your settings until it works.

You need to hold the shutter button down halfway while pointing at your subject. Once it focuses, then press the button all the way down to take the picture.

You may be too close to your subject and the autofocus is not locking in. back up a few inches and the shutter should go off. Try turning off auto-focus.
If this isn't the case it could be a shutter problem. Turn off the flash (if you don't you'll get blinded during my next step) look inside the barrel of the lens and click the shutter...you should see a little flicker inside the lens as you hit the shutter button. If you do see it, then it is in fact just the shutter...if not it's the camera itself. Be sure you are holding the shutter button down completely...as halfway only allows you o focus.

it won't take the picture until the focus is not confirmed (big dot lights up in the lower right side of the viewfinder) even though the button is pressed all the way down.
tamron lenses are notorious for slow (noisy) auto focus, so you have to be patient when focusing and half press repeatedly several times before it locks down, confirmes the focus and takes the picture.

Try this. Aim the camera at the person/object you want to take a picture of. Press the shutter button "HALF WAY DOWN" wait 2 seconds then complete by pressing all the way down to take the picture. The auto focus works on the "half way down" stroke. Some cameras have a light that goes from red to green to let you know the focus was completed. Or, just wait the 2 or so seconds.

As the others said, there are the two settings. I had a similar problem, then realized how it worked. You need to not press very hard while it focuses first. Then you can press all the way down, if you hold it all the way down, it doesn't recognize that you've already passed the first "Focus" pressure point and gone into the second "Capture" pressure point.

Because the camera has Mechanical Focus the camera button has 2 Pressures, Holding The first 1/2 of the button press will enable to Mechanical Focus to work, And then once the green dot is shown telling you its in focus, pressing the button all the way down will then take your picture !

I had the same problem. My issue was with all my lenses. I solved it by going to the menu and selecting the custom setting menu (pencil icon). Then from the right menu select the AE-L/AF-L and press OK. Then make sure it is set on AE/AF Lock. Presto...all my lenses worked on auto-focus.

PRESS AND HOLD DOWN THAT BUTTON TILL IT TAKE PICTURES or PRESS IT FOR 2sec AND leave

The cause and solution may include one of the following: The camera is not turned on. Turn on the camera. The camera is processing a picture; the camera Power ring light (on the Mode dial) blinks green. Wait until the light stops blinking before taking another picture. The card or internal memory is full. Transfer pictures to the computer, delete pictures from the camera, switch storage locations, or insert a memory card with available memory. The shutter button was not pressed. Depress the shutter button completely down. There was a failure in the focus and/or exposure. Press the shutter button halfway to set the Auto Focus (AF) and Auto Exposure (AE). When the AF/AE indicator turns green, press the shutter button completely down. The battery is exhausted. Replace or recharge the battery