Specific Cast Is Not Valid In Client Server Socket Program

I am Working on Teghax Component.Using This Component we want to find out Block title attribute of dwg file in a client server socket application.

1> We get Block title attributes properly of dwg file in windows application form using the getattribute function().

2> We get Block title Attributes properly in that way:-We take a class library where we take a class.in this class we use getattribute function().Then We access the particular class from another project

But when we use the same class(Keep same structure) in client server socket program.Then it gives an exception.i.e ,"Spaicfied cast is not valid"I am Not getting any reply form teghax developer..I attached exception screen sort.Give me Suggestion How to solve this Exception

Code given Bellow :

Public Function Get_DwgFileAttribute(ByVal Sender As ClsTcpConnection, ByVal msgTag As Byte, ByVal message As String) As String
Dictionary = GetHashtable(message)
Dim varfilepath As String = CStr(Dictionary.Item("filePath"))

[code]....