PBR / Port not in layer-3 mode

 Running a pair of S6010-ON switches on admittedly older code (9.11(0.0P9)).  Trying to place PBR on a VLAN to test redirection.  Why might the switch vlan be complaining about not being in layer-3 mode when it's clearly participating in BGP and routing??

S6010-1(conf-if-vl-500)#ip redirect-group test_dr
% Error: Port is not in Layer-3 mode Vl 500.
S6010-1(conf-if-vl-500)#

do sho run int vl500
!
interface Vlan 500
ip vrf forwarding VRF1
ip address 10.4.0.5/29
tagged fortyGigE 1/9
no shutdown