多表单提交问题？

问题困扰了一天，举步为艰啊，请高手点播下，

一个modal form表单输入一个ip后，在sqlalchemy中做一个搜索返回填写我定制的一个表单

上代码

<div class="modal-body">
                <form role="form" class="form-group" action="{{ url_for('.post') }}" method="post">
                    <fieldset>
                        <div class="form-group">
                            <input class="form-control" placeholder="Ip" name="Ip" type="Ip"  autofocus>
                        </div>
                        <input name="submit" class="btn btn-default btn-success" type="submit" 
                    value="submit">
                    </fieldset>
<!--                    <input class="from-control" placeholder="ip" name="ip" type="text"  value="">
                    <input name="submit" class="btn btn-default btn-success" type="submit" 
                    value="submit">-->
                </form>

@main.route('/post', methods=['GET', 'POST'])
@login_required
def post():

    print request.form['Ip']
    caseid=Minicomputer.query.filter_by(Ip=request.form['Ip']).first()
    print caseid
    print caseid.Hostname
    form = RepairForm(request.form)

#   if request.form["submitpost"] == "submitpost":
    if form.validate_on_submit():
#   if request.method == "POST":
        repair = Repair(Ip=form.ip.data,Series=form.series.data,Hostname=form.hostname.data,
                    ManagerIp=form.managerip.data,Comp=form.comp.data,
                    Model=form.model.data,Location=form.location.data,Box=form.box.data,
                    Important=form.important.data,Faultype=form.faultype.data,
                    Subject=form.subject.data,Body=form.body.data,Classify=form.classify.data,
                    Status=form.status.data,auth_id=current_user._get_current_object().id,
                    Owner=current_user._get_current_object().username,)
        db.session.add(repair)
        db.session.commit()
        flash('报修成功')
        return redirect(url_for('.index'))
    form.ip.data=caseid.Ip
#   form.series.data=caseid.Series
    form.hostname.data=caseid.Hostname
#   form.managerip.data=caseid.ManagerIp
#   form.comp.data=caseid.Comp
#   form.model.data=caseid.Model
#   form.location.data=caseid.Location
#   form.box.data=caseid.Box
#   form.important.data=caseid.Important
#   form.faultype.data=caseid.Faultype
#   form.classify.data=caseid.Classify
#   form.status.data=caseid.Status
    return render_template('post.html',form=form)

ip搜索能正确返回结果，

点击submit后出现以下错误。如if form.validate_on_submit():语句改为 if request.method == "POST":则直接跳过这个submit页面直接显示添加成功。中间的原理不是很清楚，帮忙

The browser (or proxy) sent a request that this server could not understand. form.validate_on_submit