diff --git a/rdpy/network/type.py b/rdpy/network/type.py
index 0dacec9..4f4559d 100644
--- a/rdpy/network/type.py
+++ b/rdpy/network/type.py
@@ -377,7 +377,11 @@ class CompositeType(Type):
         @param s: Stream
         '''
         for name in self._typeName:
-            s.readType(self.__dict__[name])
+            try:
+                s.readType(self.__dict__[name])
+            except Exception as e:
+                print "Error during read %s::%s"%(self.__class__, name)
+                raise e
             
     def __write__(self, s):
         '''
@@ -385,11 +389,15 @@ class CompositeType(Type):
         @param s: Stream
         '''
         for name in self._typeName:
-            s.writeType(self.__dict__[name])
+            try:
+                s.writeType(self.__dict__[name])
+            except Exception as e:
+                print "Error during write %s::%s"%(self.__class__, name)
+                raise e
             
     def __sizeof__(self):
         '''
-        call sizeof on each subtype$
+        call sizeof on each subtype
         @return: sum of sizeof of each public type attributes
         '''
         size = 0
@@ -733,7 +741,7 @@ class ArrayType(Type):
     but in read mode it can be dynamic
     readLen may be dynamic
     '''
-    def __init__(self, typeFactory, init = [], readLen = UInt8(), conditional = lambda:True, optional = False, constant = False):
+    def __init__(self, typeFactory, init = None, readLen = UInt8(), conditional = lambda:True, optional = False, constant = False):
         '''
         constructor
         @param typeFactory: class use to init new element on read
@@ -745,7 +753,9 @@ class ArrayType(Type):
         Type.__init__(self, conditional, optional, constant)
         self._typeFactory = typeFactory
         self._readLen = readLen
-        self._array = init
+        self._array = []
+        if not init is None:
+            self._array = init
         
     def __read__(self, s):
         '''
diff --git a/rdpy/protocol/rdp/sil.py b/rdpy/protocol/rdp/sil.py
index 40944f2..93dfa22 100644
--- a/rdpy/protocol/rdp/sil.py
+++ b/rdpy/protocol/rdp/sil.py
@@ -335,15 +335,15 @@ class OrderCapability(CompositeType):
     '''
     def __init__(self, conditional = lambda:True):
         CompositeType.__init__(self, conditional = conditional)
-        self.terminalDescriptor = String("\x00" * 16)
+        self.terminalDescriptor = String("\x00" * 16, readLen = UInt8(16))
         self.pad4octetsA = UInt32Le(0)
         self.desktopSaveXGranularity = UInt16Le(1)
         self.desktopSaveYGranularity = UInt16Le(20)
         self.pad2octetsA = UInt16Le(0)
         self.maximumOrderLevel = UInt16Le(1)
         self.numberFonts = UInt16Le(0)
-        self.orderFlags = UInt16Le(0)
-        self.orderSupport = ArrayType(UInt8, [0 for i in range(0,31)])
+        self.orderFlags = UInt16Le(OrderFlag.NEGOTIATEORDERSUPPORT)
+        self.orderSupport = ArrayType(UInt8, readLen = UInt8(32))
         self.textFlags = UInt16Le()
         self.orderSupportExFlags = UInt16Le()
         self.pad4octetsB = UInt32Le()