[TYPO3-mvc] fluid f:form in backend

[Johannes C. Schulz - EnzephaloN IT-Solutions]

Hello MVC-list!

Is there anything to know about f:form-tag in backend-modules? I think my
code is right, but the form doesn't send the object to the controller when I
hit the send-button:

FLUID:
<f:form method="post" action="saveedited" name="accreditation"
object="{accreditation}">

URL "behind" the form:
.mod.php?M=web_PsoaAccreditModule&id=151&tx_psoaaccredit_web_psoaaccreditmod
ule%5Baction%5D=saveedited&tx_psoaaccredit_web_psoaaccreditmodule%5Bcontroll
er%5D=Backend

CONTROLLER:
public function saveeditedAction(Tx_PsoaAccredit_Domain_Model_Accreditation
$accreditation){

You see, the URL doesn't contain any
"tx_psoaaccredit_web_psoaaccreditmodule%5Baccreditation%5D=171".

I hope you can help me out.

Best regards

Johannes