[TYPO3-mvc] f:form.select, multiple and selected values

[Armin Rüdiger Vieweg]

Hi all,

I've got a question about the <f:form.select /> viewhelper:
How can I make multiple values selected?

I've got such a select box:
<f:form.select property="entries" multiple="1" options="{entrylist}"  
optionLabelField="name" />

'entrylist' is a variable, which I've assigned in the controller.
Now I want that some items of the 'entrylist' are selected. I've tried to  
set a value like this:
value="{1,6}" (which means, that the options with the value 1 and 6 should  
be active)
but this has no effect (no errors, but no selected items too).

What am I doing wrong? Any ideas?

Thanks in advance!

Best regards
Armin