DOCUMENT:Q142814  11-JAN-2001  [vbwin]
TITLE   :INFO: Diagnosing "Error in loading DLL" with LoadLibrary
PRODUCT :Microsoft Visual Basic for Windows
PROD/VER:WINDOWS:4.0,5.0
OPER/SYS:
KEYWORDS:kb16bitonly kbVBp400

======================================================================
-------------------------------------------------------------------------------
The information in this article applies to:

 - Microsoft Visual Basic Professional Edition, 16-bit, for Windows, version 4.0 
 - Microsoft Visual Basic Professional Edition, 32-bit, for Windows, version 4.0 
 - Microsoft Visual Basic Enterprise Edition, 16-bit, for Windows, version 4.0 
 - Microsoft Visual Basic Enterprise Edition, 32-bit, for Windows, version 4.0 
 - Microsoft Visual Basic Professional Edition for Windows, version 5.0 
 - Microsoft Visual Basic Enterprise Edition for Windows, version 5.0 
-------------------------------------------------------------------------------

SUMMARY
=======

The error "Error in loading DLL" (code 48) occurs when you call a dynamic-link
library (DLL) procedure and the file specified in the procedure's Declare
statement cannot be loaded. You can use the Microsoft Windows API function
LoadLibrary to find out more specific information about why a DLL fails to load.

MORE INFORMATION
================

The API function LoadLibrary loads a DLL and returns either a handle or an error
code. If the return value is less than 32, it indicates one of the errors listed
below. A return value greater than or equal to 32 indicates success and you
should call the FreeLibrary function to unload the library.

LoadLibrary Error Codes
-----------------------

 0  System was out of memory, executable file was corrupt, or
    relocations were invalid.

 2  File was not found.

 3  Path was not found.

 5  Attempt was made to dynamically link to a task, or there was a
    sharing or network-protection error.

 6  Library required separate data segments for each task.

 8  There was insufficient memory to start the application.

 10 Windows version was incorrect.

 11 Executable file was invalid. Either it was not a Windows
    application or there was an error in the .EXE image.

 12 Application was designed for a different operating system.

 13 Application was designed for MS-DOS 4.0.

 14 Type of executable file was unknown.

 15 Attempt was made to load a real-mode application (developed for
    an earlier version of Windows).

 16 Attempt was made to load a second instance of an executable file
    containing multiple data segments that were not marked read-only.

 19 Attempt was made to load a compressed executable file. The file
    must be decompressed before it can be loaded.

 20 Dynamic-link library (DLL) file was invalid. One of the DLLs
    required to run this application was corrupt.

 21 Application requires Microsoft Windows 32-bit extensions.

Steps to Create Example Program
-------------------------------

The following program demonstrates how to call LoadLibrary to load a library and
display a resulting error code.

1. Create a new Standard EXE Project in Visual Basic, Form1 is created by
   default.

2. Enter the following code into the general declarations section of Form1:

      #If Win32 Then
         Private Declare Function LoadLibraryEx Lib "Kernel32" Alias "LoadLibraryExA" _
            (ByVal lpLibFileName As String, _
            ByVal hFile As Long, _
            ByVal dwFlags As Long) As Integer
         Private Declare Sub FreeLibrary Lib "Kernel32" (ByVal hLibModule As Integer)
      #Else
         Private Declare Function LoadLibrary Lib "kernel" (ByVal f$) As Integer
         Private Declare Sub FreeLibrary Lib "Kernel" (ByVal h As Integer)
      #End If

3. Enter the following code into the Form Click event handler:

         Private Sub Form_Click ()
            Dim hInst As Integer
            ' Enter the name of your DLL file inside the quotes below.
            ' The file WIN.COM is not a valid DLL and demonstrates an error.
            #If Win32 Then
               hInst = LoadLibraryEx("win.com", 0, 2)
               If hInst > 32 Then
                  MsgBox "LoadLibrary success"
                  FreeLibrary (hInst)
               Else
                  MsgBox "LoadLibrary error " + Format$(hInst)
               End If
            #Else
               hInst = LoadLibrary("win.com")
               If hInst > 32 Then
                  MsgBox "LoadLibrary success"
                  FreeLibrary (hInst)
               Else
                  MsgBox "LoadLibrary error " + Format$(hInst)
               End If
            #End If
         End Sub

4. Press the F5 key to run the program. Then click Form1. The program displays
   the error code returned from LoadLibrary. Look up this error code in the list
   of errors above to find an explanation.

Additional query words:

======================================================================
Keywords          : kb16bitonly kbVBp400 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVBA500 kbVB500 kbVB400Search kbVB400 kbVB16bitSearch
Version           : WINDOWS:4.0,5.0
Issue type        : kbinfo

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS
PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND.  MICROSOFT DISCLAIMS
ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  IN NO
EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR
ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL,
CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF
MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.  SOME STATES DO NOT ALLOW THE EXCLUSION
OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES
SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 2001.