HELP - Create HTML using window.onload + function

[embyr]

Greetings

I have been attempting to add HTML elements in my document during the window.onload to call an html injecting function using several different approaches, none of which are working. In Chrome's developer tools>scripts my most commonly occurring error is cannot call method (i.e. appendChild, innerHTML) on "null".

Below are my 3 approaches, can anyone see why they are not working?

[embyr]

APPROACH 1:

window.onload = initAll();
function initAll() {

var imgStack = [
"image1_ad",
"image2_ad",
"image3_ad"
];

//Creates IMG elements in the HTML from the array names above

for(i=0; i<imgStack.length; i++) {
var sContainer = document.getElementById('slideShowContainer');
var imgSrc = "cImg/" + imgStack[i] + ".png";
var imgElement = "<img src='" + imgSrc + "' />";
sContainer.appendChild(imgElement);
}
}

[embyr]

APPROACH 2:

window.onload = initAll();

function initAll() {
//Add Images using format: "imageName_xx", (NO comma on LAST image)
var imgStack = [
"grimreaper1_ad",
"grimreaper2_ad",
"grimreaper3_ad"
];

//Creates IMG elements from the array names in the HTML
for(i=0; i<imgStack.length; i++) {
var sContainer = document.getElementById('slideShowContainer');
var imgSrc = "cImg/" + imgStack[i] + ".png";
var imgElement = "<img src='" + imgSrc + "' />";
sContainer.innerHTML = imgElement;
}
}

[embyr]

APPROACH 3:

window.onload = initAll();
function initAll() {

var imgStack = [
"image1_ad",
"image2_ad",
"image3_ad"
];

//Creates IMG elements in the HTML from the array names above

for(i=0; i<imgStack.length; i++) {
var imgSrc = "cImg/" + imgStack[i] + ".png";
var imgElement = "<img src='" + imgSrc + "' />";
document.getElementById('slideShowContainer').appendChild(imgElement);
}
}

[Rowsdower!]

I find it best to use something like this:

window.onload=[ICODE]function(){[/ICODE]
	initAll();
[ICODE]};[/ICODE]
function initAll() {
	//Add Images using format: "imageName_xx", (NO comma on LAST image)
	var imgStack = [
		"grimreaper1_ad",
		"grimreaper2_ad",
		"grimreaper3_ad"
	];

	//Creates IMG elements from the array names in the HTML
	for(i=0; i<imgStack.length; i++) {
		var sContainer = document.getElementById('slideShowContainer');
		var imgSrc = "cImg/" + imgStack[i] + ".png";
		var imgElement = "<img src='" + imgSrc + "' />";
		sContainer.innerHTML = imgElement;
	}
}

If you don't use that "function" part the onload won't work.