Error calling WCF service that is returning list.".Debugging resource strings are unavailable ......etc etc"

Question

Ok.this is just making me frustrated...

Here is step by step of what I am trying to do (& not able to)

1. I am calling WCF service hosted in a SharePoint 2010 site from a silverlight app in same domain (So no cross doman I guess).

2. I use Linq to Sharepoint for querying the DB.

3. I am having a list "machines" in Sharepoint 2010 that is having a lookup column from Other list called "part"

4. My WCF method GetAllMachines() works perfectly well when it skips the lookup column "partname" & returns List of type machineitem.

5. But problem occurs when I add machineitemobject.parts.partsname in my Linq to Sharepoint query .

My service gives the error not found Async_ExceptionOccurred] Arguments: Debugging resource strings are unavailable."

1. Note that return type of my Method is List

2. The point to note here is that I use SPMETAL tool to generate the LINQ class that maps the lists .

So When I try to query the lookup column it tries to add List item of the type class & that is what causing the error.

Is it because I am not using datacontract in my service (but it returns the strings & all private members of machines list e.g. name,title etc)

Is it making the attribute Serialisable will solve the error ???

I am kind of lost in it ...Plss help!!

Thanks