Web Service Issue Help me ASAP

Question

Hi All,

I have great problem Om web Service Plz Help me

My code lines are:-

1. My dll Code

Class Employee
{
 Public EmployeeeId
 {
   get{}
   set{}
 }
 Likewise ..........
}

Class Users
{
 Public UserId
 {
   get{}
   set{}
 }
 Likewise ..........
}

2. My service Code has web method.....

[WebMethod]
public Object[] GetID(string str, int i, ............, Object objData)
{
  
  .
  .
  .
  .
  .
  .
  ..
  return objData;
}

This objData is of any type depending on my dll class

3. WebSite Code

when call  from my website by adding references of this serice

Like

Object obj = new Employee();

Service proxy = new Service();

Object[] objGet = proxy.GetId(string str,.........., obj);

same as User class

but it throws exception "cannot XML Document"
So these are my lines of code Plz help how can i pass user definrd object to this generic Object