Problems with image attributes

I'm not a native speaker but I give it a try :-)

I tried to add attributes of my image element directly in the attributes window, for example I set the alignment to left. But the image is then still aligned center and it won't save the setting when I save the xml file. I looked throw my dtd and also the r/w rules but they are seem to be ok.

When I set the attributes in the anchored frame window everything works just fine.

My DTD looks like these (BildPosition is the alignment, BildAusrichtung is the position of the image):

<!ATTLIST Bild       src       CDATA     #IMPLIED
                     BildPosition  (below)   #IMPLIED
                     BildAusrichtung  (left)    #IMPLIED

...

--------

My r/w rules are these one:

/* Graphic element: Bild */
element "Bild" {
is fm graphic element;
writer facet default
{
specify size in cm;
}

fm property import by reference or copy value is "ref";

attribute "src"
{
is fm attribute "src";
is fm property file;
}
  attribute "BildPosition" {
    is fm attribute "BildPosition";      
    is fm property position;
     }

    attribute "BildAusrichtung" {
    is fm attribute "BildAusrichtung";
    is fm property alignment;
    value "left" is fm property value align left;
     }

....

------------

Has anyone an idea what I do wrong?

Thanks!