make static arp, version 5.8

Hi, I have these problem

if I wont add static arp like this

[admin@router] /ip arp> add address=10.0.49.11 mac-address=00:15:6D:A0:79:17 interface=wlan1
failure: no interface provided

but

[admin@router] /ip arp> print
Flags: X - disabled, I - invalid, H - DHCP, D - dynamic

ADDRESS MAC-ADDRESS INTERFACE

0 D 10.0.49.11 00:15:6D:A0:79:17 wlan1

if I try add static route to ather interface, it's not problem. for example

[admin@router] /ip arp> add address=10.0.49.11 mac-address=00:15:6D:A0:79:17 interface=wlan2

[admin@wn-pa049-001] /ip arp> print
Flags: X - disabled, I - invalid, H - DHCP, D - dynamic

ADDRESS MAC-ADDRESS INTERFACE

0 D 10.0.49.11 00:15:6D:A0:79:17 wlan1
1 10.0.49.11 00:15:6D:A0:79:17 wlan2

Any Ideas?