Trouble with images using CE .NET 4.1

[HouseOf]

Hello,
I am constructing a webpage to be viewed on a Windows CE V4.1 computer. I have all the code working properly on my XP computer, and most will work on the CE computer; however, one line of code is giving me trouble. In the function below, I am creating a string, and then trying to set that string to the src of an <img> in my page.

function set_graph_url(TSP,DoseT,RecircT, XT) {
	var urlPath = "Linegraphdb.asp?Type=Line&TempSP=" + TSP + "&DoseTemp=" + DoseT + "&RecircTemp=" + RecircT + "&XT=" + XT;		
        document.getElementById("graphImg").src = urlPath;  /* This is the line that will not execute properly */
	}

	<img name="graphImg" id="graphImg" src="images/blank.gif" width="<% =Width %>" height="<% =Height %>" />  //This is the image I am trying to change

I realized this wouldn't work since the .getElementById is not supported by Windows CE V4.1. I have tried about 5 other variations of this code and none of them work either. Does anyone have any suggestions on how I can set the text string I create to the src of the image? I have listed below some of the other versions I have tried that haven't worked on the CE computer. Thanks for your help.

-HouseOf

function set_graph_url(TSP,DoseT,RecircT, XT) {
	var urlPath = "Linegraphdb.asp?Type=Line&TempSP=" + TSP + "&DoseTemp=" + DoseT + "&RecircTemp=" + RecircT + "&XT=" + XT; 
	document.all("graphImg").src = urlPath;  
	}

function set_graph_url(TSP,DoseT,RecircT, XT) {
	var urlPath = "Linegraphdb.asp?Type=Line&TempSP=" + TSP + "&DoseTemp=" + DoseT + "&RecircTemp=" + RecircT + "&XT=" + XT; 
	graphImg.src = urlPath;  	}

function set_graph_url(TSP,DoseT,RecircT, XT) {
		var urlPath = "Linegraphdb.asp?Type=Line&TempSP=" + TSP + "&DoseTemp=" + DoseT + "&RecircTemp=" + RecircT + "&XT=" + XT; 
	document.images.graphImg.src = urlPath;
}

var img;

function set_graph_url(TSP,DoseT,RecircT, XT) {

        var urlPath = "Linegraphdb.asp?Type=Line&TempSP=" + TSP + "&DoseTemp=" + DoseT + "&RecircTemp=" + RecircT + "&XT=" + XT; 
        img.src = urlPath;
	}

	<img name="graphImg" id="graphImg" src="C:\Documents and Settings\blank.gif" width="600" height="450" onload="img = this;"/>