Multicast join failure and socket error 59(0x3B)

Hi,I need to join 19 (or more) multicast groups, from to, on one socket. After 10 well succeed join operations, setsockopt start to return errors. See the small extract of the log: 11:54:28.059 Multicast Test: Multicast (itf 0)address add operation fails. 11:54:28.061 Multicast Test: socket error 59 11:54:29.070 Multicast Test: Multicast (itf 0)address add operation fails. … and so on. I would expect join all groups, once the driver have room to 20 for M.A.Cs, determined by MAX_MCA (on eth_mcast.c). Some debug information: 1-) The eth_add_multicast never returns an error. Also, it is never called when setsockopt have IP_ADD_MEMBERSHIP option. 2-) The socket error for the multicast join error is 59, and there is no documentation (or I was unable to find it) on Net+OS API Reference (file ApiReference.chm). 3-) eth_del_multicast is called only once. Additional information: NETOS version 60 (lib, without sources) NET+50 chip, on custom board code_extract.c with test functions and log.txt with complete log. Some one knows what is the reason? There is another documented (or not :-)) limit that I should had observed? In this case, There is a way to expand it? Thanks,