EHLLAPI IBM communicator c# Web Api not working on IIS

Question

I am trying to connect IBM communicator EHLLAPI (PCSHLL32.dll).

I have created webAPI to connect IBM PCOMM windows communicator. In visual studio I am able to establish connection with communicator and working all good. However when I deployed on IIS ,I am getting return 1 in response which means connection not established with communicator or invalid session.

Can any one guide me where I stuck on IIS level.

SO when I debug from visual studio ,here connect get value "0" which means it is connected. But On when it is hosted on IIS the service return 1.

Why I am getting 1 instead of 0.

public class EhllapiFunc
{
    [DllImport("PCSHLL32.dll")]
    public static extern UInt32 hllapi(out UInt32 Func, 
      StringBuilder Data, out UInt32 Length, out UInt32 RetC);
}

public static UInt32 Connect(string sessionID) 
{ 
 StringBuilder Data = new StringBuilder(4);
 //Data will contain the ID code of Session

 Data.Append(sessionID);
 UInt32 rc=0;
 UInt32 f=HA_CONNECT_PS; //function code
 UInt32 l=4; //lenght of data parameter
 return  EhllapiFunc.hllapi(out f, Data, out l, out rc);
 //return error code
}

In web api controller 

 public IHttpActionResult Index()
{
var connect= EhllapiClass.Connect("A");
return OK(connect);
}