PermissionSet - Request Failed error

Hi,

I have few projects communicating using ChannelSink, ServerSink and ClientSink.

I've upgraded the projects from .NET 2.0 to .NET 4.0. Before the upgrade everything worked fine.

Now, when I try to communicate , - for a specific message - my OnReceiveMessage isn't called and throwing the following exception:

System.Security.SecurityException: Request failed

Server stack trace:
    at System.Array.InternalCreate(Void* elementType, Int32 rank, Int32* pLengths, Int32* 

pLowerBounds)
    at System.Array.CreateInstance(Type elementType, Int32 Length)
    at System.Runtime.Serialization.Formatters.Soap.ObjectReader.ParseArray(ParseRecord pr)
    at System.Runtime.Serialization.Formatters.Soap.ObjectReader.ParseObject(ParseRecord pr)
    at System.Runtime.Serialization.Formatters.Soap.ObjectReader.Parse(ParseRecord pr)
System.Runtime.Serialization.Formatters.Soap.SoapHandler.StartChildren()
    at System.Runtime.Serialization.Formatters.Soap.SoapParser.ParseXML()
System.Runtime.Serialization.Formatters.Soap.ObjectReader.Run()
System.Runtime.Serialization.Formatters.Soap.ObjectReader.Deserialize(HeaderHandler, ISerParser 

serParser)
System.Runtime.Serialization.Formatters.Soap.SoapFormatter.Deserialize(Stream serializationStream, 

HeaderHandler handler)
    at System.Runtime.Remoting.Channels.CoreChannel.DeserializeSoapRequestMessage(Stream 

inputStream, Header[] h, Boolean bStrictBinding)
    at System.Runtime.Remoting.Chanels.SoapServerFormatterSink.ProcessMessage

(IServerChannelSinkStack sinkStack, IMessage requestMsg, ITransportHeaders requestHeaders, Stream 

requestStream, IMessage& responseMsg, ITransportHeaders& responseHeaders, Stream& responseStream)

Exception rethrown at [0]:
    at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage (IMessage reqMsg, IMessage 

retMSg)
    at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type)
    .
    . (some of my files)
    .
The action that failed was:
Demand
The type of the first permission that failed was:
System.Security.PermissionSet
The demand was for:<PermissionSet class="System.Security.PermissionSet" version="1" Unrestricted="true" />

The only permitted permissions were:
<PermissionSet class="System.Security.PermissionSet" version="1"><IPermission class="System.Security.Permissions.SecurityPermission", mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e version="1" Flags="SerializationFormatter" /></PermissionSet>

The method that caused that failure was:
System.Runtime.Remoting.Channels.ServerProcessing ProcessMessage(System.Runtime.Remoting.Channels.IServerChannelSinkStack, System.Runtime.Remoting.Messaging.IMessage, System.Runtime.Remoting.Channels.ITransportHeaders, System.IO.Stream, System.Runtime.Remoting.Messaging.IMessage ByRef, System.Runtime.Remoting.Channels.ITransportHeaders ByRef, System.IO.Stream ByRef)

The thing is, if I create a dummy method and add it to the sinkstack - it calls it. even if I use the same message.

Other thing is, The other messages are working just fine. only one type of messages isnt working from all the types iv'e created.

I haven't requested PermissionSet at my app at all, Any help?