Message Length Zero and packet repeating

Message Length Zero and packet repeating

I am using an TinyOS application to send packets from Radio To Serial. I
am broadcasting messages. When I read motes using Java Listen class,
sometimes I receive packet length as zero and packet counter repeating
itself. What could be the problem? I get data something like this:
00 FF FF FF 01 12 3F 06 00 00 F7 54 00 00 F6 30 02 E0 00 18 27 6C 00 18 27 75
00 FF FF FF 01 12 3F 06 00 00 F7 55 00 00 F6 31 02 E0 00 18 27 82 00 18 27 8F
00 00 FF FF 01 00 3F 06 00 00 F7 57 00 00 F6 32 02 E0 00 18 27 98 00 18 27 AA
00 FF FF FF 01 12 3F 06 00 00 F7 57 00 00 F6 33 02 E0 00 18 27 B8 00 18 27 BD
00 FF FF FF 01 12 3F 06 00 00 F7 58 00 00 F6 34 02 E0 00 18 27 CE 00 18 27 D5
Here 00 00 F7 54, 00 00 F7 55 ... are my packet counters. So, if you see
this data, I have received packet length as '00' in third row and packet
counter repeating itself in 4th row. This happens sometimes only. If you
need I can post code too. Please help.