I'm creating a GUI for the NetSend service. I created a class called
Netsend. In there are to functions. The send function is public and
the NetMessageBufferSend function is private. Below is the code I
created for this class.

Public Class Netsend

       Public Function Send(ByVal sTo As String, ByVal sMessage As
String) As Integer
           Dim iReturnValue As Integer
           Dim sReturn As String
           Dim bBuffer As Byte() =
Encoding.Unicode.GetBytes(sMessage)

           If sTo.Length And sMessage.Length <> 0 Then

               iReturnValue = NetMessageBufferSend(Nothing, sTo,
Nothing, sMessage, sMessage.Length * 2 + 2)

               Select Case iReturnValue
                   Case 0
                       sReturn = "Successfully sent message to " &
sTo
                   Case 2100
                       sReturn = ""
                   Case 2273
                       sReturn = "The message alias could not be
found on network for " & sTo
                   Case 2136
                       sReturn = "General network error occurred for
" & sTo
                   Case 5
                       sReturn = "Error: Access denied for " & sTo
                   Case 87
                       sReturn = "Invalid parameter for " & sTo
                   Case 50
                       sReturn = "This is not a supported command on
targert " & sTo
                   Case Else
                       sReturn = "Unknown return value for " & sTo
               End Select

               Return sReturn

           Else
               Return "Error: Either no computer was selected or
message was blank."
           End If

       End Function

       <DllImportAttribute("Netapi32", CharSet:=CharSet.Unicode)> _
       Private Shared Function NetMessageBufferSend(ByVal servername
As String, ByVal msgname As String, ByVal fromname As String, ByVal
buf As String, ByVal buflen As Integer) As Integer

       End Function

So my form creates a new object for this class and calls the Send
function and passes the correct arguments, Computer name and message.

Then "send function" then validates and calls the Private function
NetMessageBufferSend and assigns the return to var iReturnValue.

the "Send" function runs through a case statment to set the value of
sReturn.

Then that value of sReturn is returned to the main form.

When it tries to return the value back to a string var on the form, i
get a invalid cast error saying that it is expecting a integer. I am
able to return a integer to the main form, but why cant I return a
string?