Writing To Text Area.

I trying to but buttons for the users to write special characters to a text area in a form by clicking in a button.

<form name="form1" onSubmit="return (function1() && function2() &&
function3();">
<textarea name=t1> </textarea>
<input type=submit value="ƒ">
<input type=submit value="¼">
<input type=submit value="÷">
<input type=submit value="µ">

</form>
<script language="JavaScript"><!--
function functionName1() {
window.document.form1.t1.value = 'ƒ'
return false;
}
function functionName2() {
window.document.form1.t1.value = '¼'
return false;
}
function functionName3() {
window.document.form1.t1.value = '÷'
return false;
}
function functionName4() {
window.document.form1.t1.value = 'µ'
return false;
} //--></script>

Clicking on any button doesn't do anything but if I put just one button it works, can anyone suggest what did I do wrong?