VS 2005 - Cannot Get Content Page To Load Google Map

For some reason I cannot get my content page to load google map. Here is my code in the page load of my content page:-

Code:
If Not IsPostBack Then
ClientScript.RegisterStartupScript(Page.ClientScript.GetType, "loadmap", "loadgooglemap();", True)
End If

I have my javascript in a file called googlemap.js which holds this:-

// JScript File

Code:
function setgooglekey() {
var headID = document.getElementsByTagName("head")[0];
var script = document.createElement('script');
var referrerUrl = document.location;

[Code] ....

And finally I have in my master page :-

Code:
<script src="~/googlemap.js" type="text/javascript"></script>

Which is held in the header tags. Why it cannot see loadgooglemap?