hey guys, i need help :D

when i create any form to many any stuff, i do this for example:

	function SpeicherSprache() {
		if(Member::currentUserID()) {
				$fieldset = new FieldSet(
					new TextField(
						$name = "Sprache",
						$title = "Sprache",
						$value = ""
					...
					...
					...
					...
					new TextField(
						$name = "Muttersprache",
						$title = "Muttersprache",
						$value = ""
					)
				);
				
			$actions = new FieldSet(
				new FormAction('doSenden', 'Submit')
			);
			
			return new Form($this, 'SpeicherSprache', $fieldset, $actions);
		} else
			return false;
	}

	function doSenden($data, $form) {
		$submission = new SprachenObjekt();
		$form->saveInto($submission);
		$submission->write();
		
		Director::redirectBack();
	}

and this works. "SprachenObjekt" is just a DataObjekt i created.

soo.. now the User should have an DropdownField to choose one ob the many "SprachenObjekt" in the DB.
hier code:

	function HoleSprache() {
		$myDoSet = DataObject::get("SprachenObjekt","");
		if($myDoSet){
			$map = $myDoSet->toDropDownMap('ID', 'Sprache');
			$map = str_replace($search = array('<', '>'), $replace = array('&lt;', '&gt;'), $map);
			
			$fieldset = new FieldSet(
				new DropdownField(
					$name = "sprachen",
					$title = "Sprache w&auml;hlen",
					$source = $map,
					$value = ""
				)
			);
		}

		$actions = new FieldSet(
			new FormAction('ZeigeSprache', 'Anzeigen')
		);
		
		return new Form($this, 'HoleSprache', $fieldset, $actions);
	}
	
	function ZeigeSprache() {
		if(!isset($_POST['sprachen']))
		$_POST['sprachen'] = 1;

		$sprache = new DataObjectSet();
		
		$result = DB::query("SELECT * FROM SprachenObjekt WHERE ID = '".$_POST['sprachen']."'");
				
		if($result) {
			foreach($result as $value) {
				$eintraege =  array(
									'ID' => $value['ID'],
									'Sprache' => $value['Sprache'],
									'Kaum' => $value['Kaum'],
									'Mittel' => $value['Mittel'],
									'Gut' => $value['Gut'],
									'Muttersprache' => $value['Muttersprache']
									);
				$sprache->push(new ArrayData($eintraege));
			}
		}
		return $sprache;
	}

And this code is in my .SS file:

        $HoleSprache
        
        <% control ZeigeSprache %>
              $Sprache<br />
              $Kaum<br />
              $Mittel<br />
              $Gut<br />
              $Muttersprache<br />
        <% end_control %>

Now when i enter into this page, the Data of DB entry with "ID = 1" is shown.
And there is the DropdownField and the Button.. BUT when i click the button i just get a white page with the word "DataObjektSet".
Okay, in other forms, there is a "RedirectBack()" in the called function.. so i dont know how to handle this problem.. :S

THANKS FOR ANSWERS