Challenges using webservices in the addin in Office

[neoret]

PLEASE HELP ME -> I can't get this to work...

Do you have any experience with .NET development for Microsoft Office?
I use c#.

The application consists of an addin used in Office applications. The
addin offers extra functionality for the user - amongst these
functionalities are a button offering the user to save its document in
an external archiving system. Doing this we use webservices. It's this
webservice that challenge us a lot... The strange thing is that it
works when
used in a test-application outside of Office!

The application fails in Office (ex Word) when the method to create the
webservice object is called. The call is as follows: theWS = new
WsProxy.WebServiceService();

An Exception is thrown:

System.IO.FileNotFoundException occurred
Message="Could not load file or assembly
'SkagenWsIfCoreDoc.XmlSerializers, Version=1.0.0.0, Culture=neutral,
PublicKeyToken=null' or one of its dependencies. The system cannot find
the file specified."
Source="mscorlib"
FileName="SkagenWsIfCoreDoc.XmlSerializers, Version=1.0.0.0,
Culture=neutral, PublicKeyToken=null"
FusionLog=""
StackTrace: at System.Reflection.Assembly.nLoad(AssemblyName fileName,
String codeBase, Evidence assemblySecurity, Assembly locationHint,
StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean
forIntrospection)
at System.Reflection.Assembly.InternalLoad(AssemblyName assemblyRef,
Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean
forIntrospection)

It seems like there is missing a reference to xmlSerializers, but
System.Xml is included in the project.

Any contribution that helps solve my problem is highly appreciated