can any one tell me what may be wrong with this script I have written, excerpt following:

[PHP]if($set ="yes"){ $query.="online = 'y'"; }
if($lab !=""){ $query.=" AND Lab= '$lab'"; }
if($parcel !=""){ $query.=" AND Parcel = '$parcel'"; }
if($shape !=""){ $query.=" AND Shape = '$shape'"; }
if($color !=""){ $query.="...