My character associated to Image Target barely moves

I'm developing an android augmented reality game using unity 3d engine and vuforia extension where I need to move a character over a image target.

The problem is when I associate the character to the image target (as a child of image target) the movement is like the character is "glued" to the plane, it barely moves from his position, it moves very slowly.

I already tested without using augmented reality and the moving of the character is completly fine, so I dont know what am I doing wrong ...

Thanks in advance.