null returns when getting the radtextbox on clientscript

[Arputharaj]

I called the below function using the registerstartupscript block, but the alert returns null, so i couldnot read the object..
please help me to get out from this   

function State_Onload()
    {
    var CurrCode = $find("<%= txtCountry.ClientID%>");
    var state = $find("<%= txtStPrTe.ClientID%>");   
    var objStatelkp = document.getElementById("<%= imgSPTlookup.ClientID%>");  
    
    alert(CurrCode);
    alert(state);
    alert(objStatelkp);
    
    var cCode =  CurrCode.get_value();
    
        if (cCode == null)
        {
                        objStatelkp.style.display = 'none';
                        state.disable();       
        }
                    else if (cCode == 'US' || cCode == 'CA' || cCode == 'PR')
                    {
                        objStatelkp.style.display = 'block';
                        state.disable();
                    }
                    else
                    {
                        objStatelkp.style.display = 'none';
                        state.enable();
                    }
    }

[Shinu]

Hi Arputharaj,

Can you try following code snippet for calling the client side function and check whether this is working as expected?

CS:

protected void Button2_Click(object sender, EventArgs e)
{
    string script = "<script language='javascript' type='text/javascript'>Sys.Application.add_load(State_Onload);</script>";
    ClientScript.RegisterStartupScript(this.GetType(), "State_Onload", script);
}

Thanks,
Shinu.

[Arputharaj]

Thanks for your valuable comments shinu. But I tried that only, the html image control (which is the thrid object in the alert list) alone returns the object, but the remaing tow radtextboxes returns null.