Javascript If conditional

<script type="text/javascript" language="javascript">
var c_s = 2;
var c_st = 100;
var ferq = c_st - c_s;
var max = 500;
if((c_s < 1)||(c_st < 1)||(c_s > max)||(c_st > max)||(c_s > c_st)||(ferq < 50)||(c_s == "")||(c_st == "")) {
$("#chk").html("  <img src='images/cross.png' width='10' height='10' /> Error!");
} else {
    $("#chk").html("  <img src='images/tick.png' width='10' height='10' />");
}
</script>

returned error. why ? please help me :( how to i fix this ?