JavaScript - Checkbox Disabled Between Two Forms

I posted a thread a few days ago concerning a bit of javascript code to make checking one checkbox clear another one. I got some great, prompt help. However, I just got back to working on that web page, and realized that the functions only work on the first form on my web page. I have many forms and they are actively named using php.

Here's are the functions (these works for just the first form on the page):
Code:

<script type="text/javascript">
function undo_Changes() {
 if (document.getElementById("Complete").checked==true) {
   document.getElementById("Needs_Change").checked=false;
 }
}
function undo_Complete() {
 if (document.getElementById("Needs_Change").checked==true) {
   document.getElementById("Complete").checked=false;
 }
}
</script>

I call them from the checkboxes involved:
Code:

<input name="Complete" id="Complete" value="Yes" <?php echo($Complete=="Yes") ? "checked" : ""; ?> size="4" type="checkbox" onChange="this.style.color='#FF0000'" onClick="undo_Changes()">
<input name="Needs_Change" id="Needs_Change" value="Yes" <?php echo($Needs_Change=="Yes") ? "checked" : ""; ?>  size="4" type="checkbox" onClick="undo_Complete()">

Here's how my forms are named:
Code:

<?php $DocName = "Schedule".$count; ?> 
    <form name="<?php echo $DocName; ?>" action="ScheduleCode.php" method="post" id="<?php echo $DocName; ?>">

I've tried the following and it doesn't work at all:
Code:

<script type="text/javascript">
function undo_Changes(myForm) {
 if (myForm.getElementById("Complete").checked==true) {
   myForm.getElementById("Needs_Change").checked=false;
 }
}
function undo_Complete(myForm) {
 if (myForm.getElementById("Needs_Change").checked==true) {
   myForm.getElementById("Complete").checked=false;
 }
}
</script>
<input name="Complete" id="Complete" value="Yes" <?php echo($Complete=="Yes") ? "checked" : ""; ?> size="4" type="checkbox" onChange="this.style.color='#FF0000'" onClick="undo_Changes(this.form)">
<input name="Needs_Change" id="Needs_Change" value="Yes" <?php echo($Needs_Change=="Yes") ? "checked" : ""; ?>  size="4" type="checkbox" onClick="undo_Complete(this.form)">

Thanks for any help.
Lisa

I'm using the autofill forms plugin for firefox which can be found he

https://addons.mozilla.org/en-US/firefox/addon/4775

I use it to automatically fill various web forms, duh. But I would like certain values to be chosend randomly from a list I create.

I contacted the developer and he said the add on probably does not need a new feature because there is a 'dynamic tags' function to fill certain forms with dynamic values (e.g. the current time or date). He has given over the project to another developer and told me I probably would find a solution in a good javascript programming forum.

So here I am! Can anyone help me with this? Basically, I just need a javascript code which chooses on item from an array randomly, I guess? I'm not a programmer myself, so any help would be greatly (!) appreciated.

Thanks a lot in advance for any further guidance!

Note: Here are sample dynamic tags from the plugin:

<datetime> new Date().toLocaleString()
<useragent> navigator.userAgent
<langcode> navigator.language
<resolution> screen.width+'x'+screen.height
<clipboard> this.getClipboardText()

So here's what i want to do:

i have 2 checkboxes,

when Checkbox A is checked, i want to automatically check the checkbox B. When A is unchecked, then uncheck B

how can i do that?

thanks a lot !

hi, my problem is that .disabled only work in Firefox.
How do i make it work in other browses?
Below is the code i attached

Code:

if (output=="Available")
        document.register.submitBtn.disabled=false;
    else
        document.register.submitBtn.disabled=true;

i have an assignment to solve in which i have given two checkboxes one is enabled and another one is disabled n m required that if we select enable checkbox the disabled checkbox may also be selected automatically can any one help out for its coding please
Thanks