Assembly not found during BinaryFormatter.Deserialize

[Fruber Malcome]

I'm getting a very weird exception and hoping someone may be able to help.

I have an Office Add-In that lives in a .dll (for email reference ai.dll)
ai.dll makes calls into the core part of the application implementation in
another .dll (let's call that app.dll).
app.dll makes a function call into another dll (let's call that one
dep.dll).

dep.dll has some code in it where it deserializes a memorystream using a
binaryformatter .
I step through the code in this function and it properly - opens the binary
file, puts it into a BinaryReader, then I get the byte[] by calling the
br.ReadBytes(). , I then create a new memory stream (ms) using that byte[] in
the constructor, I create a new binaryformatter with the default
constructor, I then say:
object obj = bf.Deserialize( ms );

And it's on this line of code that I get: "Cannot find the assembly
dep.dll"??

I look at the stack trace and it's in the dep.dll assembly (which is where I
stepped this far in the code).

The Stack trace is below:
at
System.Runtime. Serialization.F ormatters.Binar y.BinaryAssembl yInfo.GetAssemb ly()
at
System.Runtime. Serialization.F ormatters.Binar y.ObjectReader. GetType(BinaryA ssemblyInfo
assemblyInfo, String name)
at System.Runtime. Serialization.F ormatters.Binar y.ObjectMap..ct or(String
objectName, String[] memberNames, BinaryTypeEnum[] binaryTypeEnumA , Object[]
typeInformation A, Int32[] memberAssemIds, ObjectReader objectReader, Int32
objectId, BinaryAssemblyI nfo assemblyInfo, SizedArray
assemIdToAssemb lyTable)
at System.Runtime. Serialization.F ormatters.Binar y.ObjectMap.Cre ate(String
name, String[] memberNames, BinaryTypeEnum[] binaryTypeEnumA , Object[]
typeInformation A, Int32[] memberAssemIds, ObjectReader objectReader, Int32
objectId, BinaryAssemblyI nfo assemblyInfo, SizedArray
assemIdToAssemb lyTable)
at
System.Runtime. Serialization.F ormatters.Binar y.__BinaryParse r.ReadObjectWit hMapTyped(Binar yObjectWithMapT yped
record)
at
System.Runtime. Serialization.F ormatters.Binar y.__BinaryParse r.ReadObjectWit hMapTyped(Binar yHeaderEnum
binaryHeaderEnu m)
at System.Runtime. Serialization.F ormatters.Binar y.__BinaryParse r.Run()
at
System.Runtime. Serialization.F ormatters.Binar y.ObjectReader. Deserialize(Hea derHandler
handler, __BinaryParser serParser, Boolean fCheck, IMethodCallMess age
methodCallMessa ge)\r\n at
System.Runtime. Serialization.F ormatters.Binar y.BinaryFormatt er.Deserialize( Stream
serializationSt ream, HeaderHandler handler, Boolean fCheck,
IMethodCallMess age methodCallMessa ge)
at
System.Runtime. Serialization.F ormatters.Binar y.BinaryFormatt er.Deserialize( Stream
serializationSt ream, HeaderHandler handler)
at
System.Runtime. Serialization.F ormatters.Binar y.BinaryFormatt er.Deserialize( Stream
serializationSt ream)
at that line of code mentioned above


Any help would be appreciated.
thanks