getting error when trying to change asp.net label values using JavaScript

I have an asp.net website. I want to change the label values in a JavaScript function.

Here is my code,

<td id="m1" runat"server" onclick = "createChart_Jan"></td>
<asp:Label ID="lblGeneral" runat="server" Text="" Font-Bold="true" Font-Size="Medium"></asp:Label>

JavaScript,

function createChart_Jan() {
   var month = 1;
   var d = new Date();
   var month_current = d.getMonth() + 1;
   if(month > month_current)
   {
      document.getElementbyId("lblGeneral").innerHTML = "0";
   }
   else
   {
      document.getElementbyId("lblGeneral").innerHTML = "500";
   }
}

But I am getting "Uncaught TypeError: undefined is not a function" error when I click on td element.

Any idea on what is wrong with above code?