Are you getting question mark and when you change the colour and the whole art board turning grey no matter what colour you choose? Here you go with the solution.
Here are my answers to your questions regarding live trace in Illustrator
Reason:
This is because document colors are set to grayscale mode.
Solution:
Go to the color panel, click the down-arrow in the top right corner, and change there Gray Scale to RGB/CMYK as per your requirement.
Step 1:
Place the image which you want to trace.
Step 2:
Select the image and make Image Trace from Object panel.
Object -> Image trace -> Make and Expand
Ungroup the Traced Image by press Cmd/Ctrl+Shift+G or right click on the image and select Ungroup.
Now select the shape and change the color .
But here the color changed into gray rather than purple.
Now you can able to change the color of the traced image.