Disable "Create invoice" button

Hi,

I have a problem with "Create Invoice" button. When I click it and my invoice created, it isn't disabled.So we can have so many related invoice and it is bad. I want to be disabled it, when first invoice was created and no one can click it again.

I used javascript but it is disabled just during the creating invoice and after that it is enable.

Please help me

This is my code:

function FrmOnSave(prmContext) {
    // Local variable to store value indicating how the save event was initiated by the user.
    var wod_SaveMode, wod_SaveEventVal;

    // Change the Save Event Value as per required Save Event
    wod_SaveEventVal = 19;

    if (prmContext != null && prmContext.getEventArgs() != null) {

        wod_SaveMode = prmContext.getEventArgs().getSaveMode();

        if (wod_SaveMode == wod_SaveEventVal) {
            var buttonID = "salesorder|NoRelationship|Form|Mscrm.Form.salesorder.MainTab.Actions-LargeMediumLarge-0";
            var btn = window.top.document.getElementById(buttonID);
            if (btn) {
                btn.disabled = false;
            }