Hi @suresh kaliappa ,

Make it onChange and uncheck the isolate script 

Refer screenshot below

script:

function onChange(control, oldValue, newValue, isLoading) {
    var reqForLabel = $('label.sc_req_item.requested_for');
	var reqForField = $('sys_display.sc_req_item.requested_for');

    if (!reqForLabel || !reqForField)
        return;

    if (!newValue) {
        reqForLabel.setStyle({
            backgroundImage: ""
        });
        reqForField.setStyle({
            color: ""
        });
        return;
    }
    g_form.getReference('requested_for', vipCallerCallback);
}

function vipCallerCallback(caller) {
    var reqForLabel = $('label.sc_req_item.requested_for').down('label');
	var reqForField = $('sys_display.sc_req_item.requested_for');

    if (!reqForLabel || !reqForField)
        return;

    //check for VIP status
    if (caller.vip == 'true') {
        var bgPosition = "95% 55%";
        if (document.documentElement.getAttribute('data-doctype') == 'true')
            bgPosition = "5% 45%";

        reqForLabel.setStyle({
            backgroundImage: "url(images/icons/vip.gif)",
            backgroundRepeat: "no-repeat",
            backgroundPosition: bgPosition,
            paddingLeft: '30px'
        });
        reqForField.setStyle({
            color: "red"
        });
    } else {
        reqForLabel.setStyle({
            backgroundImage: ""
        });
        reqForField.setStyle({
            color: ""
        });
    }
}

Please mark my answer as helpful/correct if it resolves your query.

Regards,
Chaitanya