Look Up Record Default Entity Scripts Not Working in CRM 2013

Hello all,

I can't seem to get the scripts in my email activtity form to work in CRM 2013. I have the following functions in my OnLoad event for the email activity form:

function DefaultToLookUp()
{
document.getElementById('to').setAttribute('defaulttype', '2');
Xrm.Page.getControl('to').setDefaultView('A2D479C5-53E3-4C69-ADDD-802327E67A0D');
}

function DefaultRegardingLookUp()
{
document.getElementById('regardingobjectid').setAttribute('defaulttype', '3');
Xrm.Page.getControl('regardingobjectid').setDefaultView('9EB361B4-67AC-4830-8ABF-2D29EFBAEE2C');
}

These used to set the default entity to contact for the "To" field and opportunity for the "Regarding"field in CRM 2011. Your assistance is appreciated!