Problem with static ARP on router TP-Link TD8840

[dytu iuyr]

hello,

My router TP-Link TD8840 uses Busybox v.1.00 and there is ARP tool on 
it. I can  add new entry using: "arp add IP Adress MAC Adress". The 
problem is that I can't save that entry permanently. After rebooting 
that entry is missing...
What am i doing wrong? Is it common problem of Busybox or maybe its only 
problem with my version  of busybox and my arp applet? What can I do?

Any help and ideas are welcomed ;)
sly

----------------------------------------------------
Jasienica-powrót! "Rzeczypospolita Obojga Narodów" 
Pawła Jasienicy 
już w księgarniach! 
http://klik.wp.pl/?adr=http%3A%2F%2Fcorto.www.wp.pl%2Fas%2Frzeczypospolita.html&sid=85