problem with form plug-in, form is loaded "later"

problem with form plug-in, form is loaded "later"

jquery or my way using it seem to have problems with forms that are loaded after some user interaction via ajax. so the hole form and its id isn't present at beginning.

if some useraction occur a form is evaluated and a parameter depended form is "injected" via ajax on same page.

i uesed allways only formSerialize from this plugin and my own ajax function:

function sendForm(formid,destination,prefix) {
       var form = jQuery(formid);
       var addstring=form.formSerialize();
       fetch(prefix + addstring,destination, "replace", "event");
}

this works fine but not in this special case. in this case only the first submit of the injected form works fine. after this the data from the first submission is somehow cached and is submitted until i reload the hole site. i proofed this via an alert in my sendform function, the addstring doesn't changes after first submit 'til reload of the page (but the "values" in form fileds have changed! ).

so i tried the standard procedure:
$(document).ready(function() {
   $('#assign_form').ajaxForm();
});

i put this code at the end of the injected form and made my submit button also a standard submit button:
<input type="submit" value="buchen">
the head of the form is:
<form id="assign_form" method="GET" action="index.php">

but this isn't working neither, it results in a normal submit with page reload the "ready wraper" and "ajax.Form" seem to be ignored completly? (no error)

so i need a way to submit forms via ajax that are injected by ajax sometime after initial page load.

any ideas?

thx in advance