Hello Sivasravan!
You have a little problem. Like you said you are using a TEXTBOX with MULTINE type. Using that object is almost the same thing using a TEXTAREA and this object doesn't have MULTINE type too.
My sugestion is using a JAVASCRIPT FUNCTION to count the length of the TEXTBOX. Try this:
<SCRIPT language="text/javascript">
function CountLength(ObjectThatYouWant)
{
LenTxt = ObjectThatYouWant.value.length;
if (LenTxt > 100)
{
ObjectThatYouWant.value = ObjectThatYouWant.value.substring(0,100);
}
}
</SCRIPT>
Then call this function on client side in this button events : onkeydown, onkeyup, onchange, onblur
HAVE NICE DEBUGS!