The problem is that in Stick, when I upload a photo, it appears the message "No official build is available for this camera". 
Click the "show log" button and copy the log here.
Since you're using Windows, you could do the installation like this:
- format SD card in camera
- put the card in a card reader, connect it to the computer
- extract the content of the "complete" CHDK package (from here) to the card
- put the card in camera, do the "fw update"
- CHDK should start and you should see an onscreen ALT button (actually, I don't know how that looks)
- press ALT then MENU, navigate to "miscellaneous stuff" -> "SD card" -> "make card bootable"
- switch the cam off, write protect the card with the plastic switch, put it back
- CHDK should now autoboot
- you can use cards up to 32GB with this method (special utilities are needed for bigger cards)
Thank you! I try this process that you wrote, and I'll let you know.
This is the Show Log:
STICK - Dave Mitchell 1.09
OS Type=2 OS Version=7
engine link established
Is an admin
Running on a 64-bit machine
elevated=false
maxsize=64000 testsize=70000 (64GB)
STICK needs Administrator permission - start it by double-clicking STICKX.CMD
IMG_0006.JPG dropped
H:\DCIM\101___07\IMG_0006.JPG is being processed
fm=16843008 icm=3180000 fms='Firmware Version 1.01'
Checking official builds
Checking if pre-loaded zip C:\Users\Pellicano\Desktop\chdk\test101a.zip exists
zip C:\Users\Pellicano\Desktop\chdk\test101a.zip not found
- no build found for Canon IXUS 240 HS 101a
No official build is available for this camera
Processing completed
IMG_0006.JPG dropped
H:\DCIM\101___07\IMG_0006.JPG is being processed
fm=16843008 icm=3180000 fms='Firmware Version 1.01'
Checking official builds
Checking if pre-loaded zip C:\Users\Pellicano\Desktop\chdk\test101a.zip exists
zip C:\Users\Pellicano\Desktop\chdk\test101a.zip not found
- no build found for Canon IXUS 240 HS 101a
No official build is available for this camera
Processing completed
IMG_0010.JPG dropped
H:\DCIM\101___07\IMG_0010.JPG is being processed
fm=16843008 icm=3180000 fms='Firmware Version 1.01'
Checking official builds
Checking if pre-loaded zip C:\Users\Pellicano\Desktop\chdk\test101a.zip exists
zip C:\Users\Pellicano\Desktop\chdk\test101a.zip not found
- no build found for Canon IXUS 240 HS 101a
No official build is available for this camera
Processing completed
