Exception while creating XmlSerializer with XmlAttributeOve rrides.

[harshal.borade]

I am using XmlSerializer with XmlAttributeOve rrides. The
XmlAttributeOve rrides are used for properties which hold element/s
derived from "AbstractMessag e" type.

System.Xml.Seri alization.XmlRo otAttribute(Nam espace = "http://
www.TestNameSpa ce.org/Test-4-4", IsNullable = false)]
class Root
{
[System.Xml.Seri alization.XmlEl ementAttribute( Type =
typeof(Abstract _message), ElementName = "Message", IsNullable =
false)]
public virtual Abstract_messag e Message
{
get { return this._messageFi eld; }
set{ this._messageFi eld = value; }
}

[System.Xml.Seri alization.XmlEl ementAttribute( Type =
typeof(BatchMes ssage), ElementName = "Batch", IsNullable = false)]
public virtual Batch_tCollecti on Batch
{
get { return this._batchFiel d; }
set{ this._batchFiel d = value; }
}
}

[System.Xml.Seri alization.XmlTy peAttribute(Nam espace = "http://
www.TestNameSpa ce.org/Test-4-4")]
public class BatchMesssage
{
///
[System.Xml.Seri alization.XmlEl ementAttribute( "Hdr", Order =
0, IsNullable = false)]
public BatchHeader_t Hdr
{
get{ return this._hdrField; }
set { this._hdrField = value; }
}
[System.Xml.Seri alization.XmlEl ementAttribute( "Message", Order
= 1, IsNullable = false, Type = typeof(Abstract _message_t))]
public Abstract_messag e_tCollection Messages
{
get { return this._messageFi eld; }
set { this._messageFi eld = value; }
}
}

where type "Batch_tCollect ion" is a collection of "BatchMessa ge" type
items.
For type "Root" "BatchMessa ge" I provide XmlAttributeOve rrides for
property "Message" & "Messages" respt. :

System.Xml.Seri alization.XmlAt tributeOverride s attribOverrides = new
System.Xml.Seri alization.XmlAt tributeOverride s();
System.Xml.Seri alization.XmlAt tributes msgAttribs = new
System.Xml.Seri alization.XmlAt tributes();
msgAttribs.XmlE lements.Add(new
System.Xml.Seri alization.XmlEl ementAttribute( "TestMessageRoo t",
typeof(TestMess age)));
attribOverrides .Add(typeof(Roo t), "Message", msgAttribs);
attribOverrides .Add(typeof(Bat chMesssage), "Message", msgAttribs);

where type "TestMessag e" is derived from "AbstractMessag e" type.
When I try to instantiate the XmlSerializer with the above
XmlAttributeOve rrides as parameter to the constructor it throws the
following exception:

Exception:
System.InvalidO perationExcepti on was caught
Message="There was an error reflecting type 'Root'."
Source="System. Xml"
StackTrace:
at
System.Xml.Seri alization.XmlRe flectionImporte r.ImportTypeMap ping(TypeModel
model, String ns, ImportContext context, String dataType,
XmlAttributes a, Boolean repeats, Boolean openModel)
at
System.Xml.Seri alization.XmlRe flectionImporte r.ImportElement (TypeModel
model, XmlRootAttribut e root, String defaultNamespac e)
at
System.Xml.Seri alization.XmlRe flectionImporte r.ImportTypeMap ping(Type
type, XmlRootAttribut e root, String defaultNamespac e)
at System.Xml.Seri alization.XmlSe rializer..ctor( Type type,
XmlAttributeOve rrides overrides, Type[] extraTypes, XmlRootAttribut e
root, String defaultNamespac e, String location, Evidence evidence)
at System.Xml.Seri alization.XmlSe rializer..ctor( Type type,
XmlAttributeOve rrides overrides, Type[] extraTypes, XmlRootAttribut e
root, String defaultNamespac e)

Inner Exception: There was an error reflecting property 'Batch'.
Inner Exception: There was an error reflecting type 'BatchMessage'.
Inner Exception: Inconsistent sequencing: if used on one of the
class's members, the 'Order' property is required on all particle-like
members, please explicitly set 'Order' using XmlElement, XmlAnyElement
or XmlArray custom attribute on class member 'Messages'.
In the above case if I remove the sequencing property ("Order") from
the XmlElementAttri bute applied on BatchMessage member properties, the
thing seems to work correctly.

Am I using the XmlAttributeOve rride in the right place? Any help on
the above will be appreciated.
Thanks in advance.