Index: umit/pm/backend/scapy/translator.py
===================================================================
--- umit/pm/backend/scapy/translator.py	(revision 5606)
+++ umit/pm/backend/scapy/translator.py	(working copy)
@@ -36,6 +36,21 @@
         'bootp' : (BOOTP, None),
             'dhcp' : (DHCP, None),
         'nbt' : (NBTSession, None),
+        'dns' : (DNS, None),
+        'dnsqr' : (DNSQR, None),
+        'dnsrr' : (DNSRR, None),
+    'raw' : (Raw, None),
+}
+add_smb = False
+try:
+    from umit.pm.backend.scapy.wrapper import SMBHeader
+    add_smb = True
+except ImportError:
+    add_smb = False
+
+if add_smb:
+
+    global_trans_smb = {
         'smb' : (SMBHeader, None),
 
         'smbneg_resp' : (SMBNegociate_Response, None),
@@ -45,11 +60,7 @@
 
         'smbsax_req' : (SMBSetup_AndX_Request, None),
         'smbsax_req_as' : (SMBSetup_AndX_Request_Advanced_Security, None),
-
         'smbtcax_req' : (SMBTree_Connect_AndX_Request, None),
+    }
+    global_trans.update(global_trans_smb)
 
-        'dns' : (DNS, None),
-        'dnsqr' : (DNSQR, None),
-        'dnsrr' : (DNSRR, None),
-    'raw' : (Raw, None),
-}