how to submit GET form with jstl parameter

how to submit GET form with jstl parameter

i have following form it does not show jstl parameter in url after submiting
<form action="Contactus.jsp?param1=${value1}" method="get">
<input type="submit" value="${btnregister}" id="registration-link">
</form>
After submitting form it only shows Contactus.jsp? and param1 disappears.
Why?