Form will not submit in IE 11, successful in all others - html

Question

I am a newb to programming, this is my first question here.
I have a bootstrap modal that opens up to a Contact Us form. In Firefox, the form submits postback as expected. In IE 11 clicking the send button just hangs, nothing. The close window buttons work as do the required attributes for text input fields.
I have seen other similar questions, but I am not missing name attributes on any field or button. I am also not duplicating the type="submit" attributes in the tag. I have experimented with using button type="submit" and every other way I can think of doing it. The modal and form elements all work except for the submission. The button behaves as though it is being clicked but nothing changes, nothing is submitted. Any help would be terrific!
Relevant Code:
<form class="form-horizontal" method="post" name="PortalContactUsForm" id="PortalContactUsForm">
<input type="submit" form="PortalContactUsForm" name="SendEmailButton" id="SendEmailButton" class="btn btn-primary" value="Send">
The complete Modal and form code:
<div id="myPortalModal" class="modal hide fade" tabindex="-1" role="dialog" aria-labelledby="myPortalModalLabel" aria-hidden="true">
<div class="modal-header">
<button type="button" name="ModalCloseButton" class="close" data-dismiss="modal" aria-hidden="true">x</button>
<h3 id="myPortalModalLabel">Contact Us</h3>
</div>
<div class="modal-body">
<h4>Send <cfoutput>#sub_merchant.companyname#</cfoutput> an email by filling out the form below.</h4><br>
<form class="form-horizontal" method="post" name="PortalContactUsForm" id="PortalContactUsForm">
<div class="control-group">
<label class="control-label" for="Account" name="lblAccount" id="lblAccount" form="PortalContactUsForm">Account</label>
<div class="controls">
<input type="text" form="PortalContactUsForm" name="Account" id="Account" value="<cfoutput>#customer.account#</cfoutput>" readonly>
</div>
</div>
<div class="control-group">
<label class="control-label" for="FirstName" name="lblFirstName" id="lblFirstName" form="PortalContactUsForm">First Name</label>
<div class="controls">
<input type="text" form="PortalContactUsForm" name="FirstName" id="FirstName" value="<cfoutput>#customer.firstname#</cfoutput>" readonly>
</div>
</div>
<div class="control-group">
<label class="control-label" for="LastName" name="lblLastName" id="lblLastName" form="PortalContactUsForm">Last Name</label>
<div class="controls">
<input type="text" form="PortalContactUsForm" name="LastName" id="LastName" value="<cfoutput>#customer.lastname#</cfoutput>" readonly>
</div>
</div>
<div class="control-group">
<label class="control-label" for="Email" name="lblEmail" id="lblEmail" form="PortalContactUsForm">Your Email</label>
<div class="controls">
<input type="email" form="PortalContactUsForm" name="Email" id="Email" value="<cfoutput>#customer.email#</cfoutput>">
</div>
</div>
<div class="control-group">
<label class="control-label" for="ConfirmEmail" name="lblConfirmEmail" id="lblConfirmEmail" form="PortalContactUsForm">Confirm Email</label>
<div class="controls">
<input type="email" form="PortalContactUsForm" name="ConfirmEmail" id="ConfirmEmail" value="">
</div>
</div>
<div class="control-group">
<label class="control-label" for="PhoneNum" name="lblPhoneNum" id="lblPhoneNum" form="PortalContactUsForm">Your Phone</label>
<div class="controls">
<input type="tel" form="PortalContactUsForm" name="PhoneNum" id="PhoneNum" value="<cfoutput>#customer.phone#</cfoutput>">
</div>
</div>
<div class="control-group">
<label class="control-label" for="MsgBody" name="lblMsgBody" id="lblMsgBody" form="PortalContactUsForm">Questions/Comments</label>
<div class="controls">
<textarea rows="3" form="PortalContactUsForm" name="MsgBody" id="MsgBody" placeholder="No html here, just plain text please." required></textarea>
</div>
</div>
<div class="control-group pull-right">
<label class="checkbox">
<input type="checkbox" form="PortalContactUsForm" name="SendCCCheckbox" id="SendCCCheckbox">
Check this box to receive a copy of this email at the address above.
</label>
</div>
<cfoutput>
<input type="hidden" form="PortalContactUsForm" name="postback" id="postback" value="true">
<input type="hidden" form="PortalContactUsForm" name="mailsend" id="mailsend" value="true">
<input type="hidden" form="PortalContactUsForm" name="lname" id="lname" value="#trim(form.lname)#">
<input type="hidden" form="PortalContactUsForm" name="zip" id="zip" value="#(len(trim(form.zip)) > 5 ? left(trim(replace(form.zip, "-", "", "all")), 5) : trim(form.zip))#">
<input type="hidden" form="PortalContactUsForm" name="pin" id="pin" value="#trim(replacelist(pin, "-, ", ""))#">
</cfoutput>
</form>
</div>
<div class="modal-footer">
<button class="btn" name="CloseModalButton" data-dismiss="modal" aria-hidden="true">Close</button>
<input type="submit" form="PortalContactUsForm" name="SendEmailButton" id="SendEmailButton" class="btn btn-primary" value="Send">
</div>
</div>