USB devices do not map from Wyse clients

We are running a Citrix XenApp 6 environment and Citrix policies are in place to allow USB devices and client drives to map. USB flash drives map through to a Citrix session when used from PC's, but never from any Wyse clients. Following is the WNOS.ini file in use. Please let me know what I'm missing.

;************************************************* ************
;* General 1 *
;************************************************* ************

signon=0
autoload=0
EnableLocal=1
MaxVNCD=1 VNCD_8bits=yes
VncPassword="Wyse" Encrypt=no
VncPrompt=No Accept=5 ActiveVisible=no

;************************************************* ************
;* Display *
;************************************************* ************

;Screensaver="5" LockTerminal=no Type=2 Image=screensaver.JPG
Screensaver="20" LockTerminal=no Type=0

;************************************************* ************
;* Time *
;************************************************* ************

Timeserver=132.163.4.102 Timeformat="12-hour format" Dateformat=mm/dd/yyyy
TimeZone='GMT - 07:00' ManualOverride=yes Daylight=yes Start=030207 End=110107 TimeZoneName="Mountain Standard Time" DayLightName="Mountain Daylight Time"

;************************************************* ************
;* ICA *
;************************************************* ************

PnliteServer=http://COCITRIX ReconnectAtLogon=2 ReconnectFromButton=2 AutoConnectlist="ALL"
SessionConfig=ICA DesktopMode=Fullscreen MapDisksUnderZ=yes

;************************************************* ************
;* Network *
;************************************************* ************

SignOn=no
DomainList="CMC"

;************************************************* ************
;* General Session *
;************************************************* ************

SessionConfig=ALL UnmapPrinters=no UnmapSerials=yes Smartcards=yes
LowBand=no noreducer=no Seamless=yes OnDesktop=no MapDisks=yes UnMapUSB=yes EnableLocal=no HideDefault=yes