CRM 2011- Disable Sub grid

function VisibleGunTransactionEntries() {
var statusreason=Xrm.Page.data.entity.attributes.get("statuscode");
var reason = statusreason.getValue();
if (reason != 170000000) {

    var objNavItem = Xrm.Page.ui.navigation.items.get("nav_jmh_jmh_guntransaction_jmh_guntransactionentry_guntransaction");
        objNavItem.setVisible(false);
        disableSubgrid('subgrid1');
}
}
function disableSubgrid(subgridName) {
    document.getElementById(subgridName + "_span").disabled = "true";
}