DOCUMENT:Q179027  08-JAN-1998  [vbwin]
TITLE   :PRB: Variable Not Defined Error Message When Using a Constant
PRODUCT :Microsoft Visual Basic for Windows
PROD/VER:WINDOWS:4.0,5.0
OPER/SYS:WINDOWS
KEYWORDS:VB4ALL VB4WIN vb5all VBKBAX_VBKBComp kberrmsg

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The information in this article applies to:

 - Microsoft Visual Basic Learning, Professional, and Enterprise Editions
   for Windows, version 5.0
 - Microsoft Visual Basic Standard, Professional, and Enterprise Editions,
   16-bit and 32-bit, for Windows, version 4.0
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SYMPTOMS
========

The following error message displays when you attempt to use a predefined
constant for an automation server:

   "Compile Error:
   Variable Not Defined"

For example, you may receive this error when you try to use the constant
xlR1C1 from the Microsoft Excel Object Library.

CAUSE
=====

You are using late binding on an ActiveX component.

RESOLUTION
==========

You can use early binding by referencing the object library for the
automation server in your project. Click References on the Project menu to
select the object library.

 - or-

If you want to use late binding, declare your own constant and assign it to
the numeric value of the predefined constant. For example, the constant
xlR1C1 is equivalent to -4150. Therefore, you could add the following to
your project.

      Const xlR1C1 = -4150

STATUS
======

This behavior is by design.

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

Late Binding occurs when you declare a variable As Object, As Form, As
Control, or As Variant and Visual Basic cannot determine at compile-time
what sort of object reference the variable will contain. Therefore, Visual
Basic must use late binding to determine at run-time whether the actual
object has the properties and methods you call using the variable.

Early Binding occurs when you make a reference to the object library at
design-time. Visual Basic then knows what object library contains the
properties and methods when you make your variable call. Early Binding also
provides some performance gains.

REFERENCES
==========

"How Binding Affects ActiveX Component Performance" in the Visual Basic
Component Tools Guide, version 5.0.
======================================================================
Keywords          : VB4ALL VB4WIN vb5all VBKBAX_VBKBComp kberrmsg
Version           : WINDOWS:4.0,5.0
Platform          : WINDOWS
Issue type        : kbprb

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