Returns the total number of records in the Grid

Good afternoon,

I'm trying from inside the quotation, take the amount of items Quotation Products grid, I'm utillizando the code below, but to run it appears the "undefined error" message, the code was what I found in the SDK.

And the grid has two records

function test()
{
       var filteredRecordCount = Xrm.Page.getControl("Produtos").getGrid().getTotalRecordCount();
      alert(filteredRecordCount);
}

Thank you