VLAN Configuration
This Cisco (IOS 12.2(55)SE2) differentiates between a VLAN and an Extended VLAN (VID 1007 or higher).
By the default the switch ships in VTP mode, so you have to switch that to transparent mode and then manually define the VLAN before you can use it.
Switch(config)# vtp mode transparent
Switch(config)# vlan 3994
Switch(config-vlan)# end
Switch# copy running-config startup config
Now you can assign the VLAN normally:
Switch(config)#interface GigabitEthernet1/0/47
Switch(config-if)#switchport access vlan 3994
Switch(config-if)#exit