Collabora online --> imprint integration

i am trying to integrate collabora online app (richdocuments) in the imprint-app but i get several errors:

css configuration:
.richdocuments{
display:block;
width:135px;
height:135px;
background:url("…/img/dash/img/135x135/img/document.png") no-repeat;
}

the picture is not showing and when i check the console i get these errors:

but the other apps work just fine:

anyone with the same problem?