orbit mouse camera animation movement script

ok i have this script from unity guide

function Update () { if (Input.GetAxis("Vertical") > 0.2) animation.CrossFade ("walk"); else animation.CrossFade ("idle"); }

   is attached with the mouse orbit camera 

so when i move forward it animates and when i stop moving it makes the idle animation. the problem is when i move backwards or side to side, it doesn´t perform the right animation

??? sorry im a 3d artist not a programer...