CRM online 2016 getTotalRecordCount

Hi,

I would like to display the total number of rows in Contacts subgrid on Account form. My code is:

function recordcount()
{
    var TRC = Xrm.Page.getControl("accountcontactsgrid").getGrid().getTotalRecordCount();
    Xrm.Page.getAttribute("eg_recordcount").setValue(TRC)
}

But I am getting error:

TypeError: Unable to get property 'getGrid' of undefined or null reference at recordcount

Can somebody help.

Br