Hi Soltani.
The latest SVN versions of Wireshark support multiple link types in pcap-ng files, although to capture on non-Ethernet link types you have to use dumpcap. There was an issue where pcap-ng files created by earlier versions of Wireshark weren't being handled by newer versions, and vice-versa (i.e. packets appear, but link type information is missing).
If they help, there are a number of sample files at
http://wiki.wireshark.org/Development/PcapNg, at
http://code.google.com/p/understand/downloads/list and there might be some floating around this mailing list, although most were sent to developers off-list to examine, from what I can tell.
If you need anything else, just ask.
Tyson.
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