Unable to call Javascript function from child page

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ASP.NET4

hello friends,
I was trying to call javascript function in child page
I have written following JS function in contentholder

function CreateGridHeader(pnlGVForecast, GridView1, HeaderDiv) {
....
}

I bind this function in Page_load in following way

 protected void Page_Load(object sender, EventArgs e) {
ClientScript.RegisterStartupScript(this.GetType(), "CreateGridHeader", "<script>CreateGridHeader('pnlGVForecast', 'gvForecastSummary','HeaderDiv');</script>");
}

I tried to check the source code at runtime, what I found is the change in ID of controls

<br />
cphPage_pnlGVForecast for pnlGVForecast, cphPage_gvForecastSummary for gvForecastSummary<br />

i tried the following code too

ClientScript.RegisterStartupScript(this.GetType(), "CreateGridHeader", "<script>CreateGridHeader('cphPage_pnlGVForecast', 'cphPage_gvForecastSummary','HeaderDiv');</script>");

Still the javascript function is not getting called

Any solution??

Thanks in advance