multiplexor issue, messages not processed

HI,

I'm using a J1939 PROP _B massage that is multiplexed,  The index in in byte 3 (mask 0XFF0000) . If I remove the page protocol, the massage is processed  and I get the data. I can manually process the Index and get the data, but when I use the index and page mask the massage is not processed.  Has anyone see this?  index is 8 bits.  I have 16 index's values starting from 0 to 16 defined.