PRB: Excel Automation Fails Second Time Code Runs

• Microsoft Visual Basic Learning, Professional, and Enterprise Editions for Windows, versions 5.0, 6.0
• Microsoft Visual Basic Standard, Professional, and Enterprise Editions for Windows, version 4.0
• Microsoft Excel 97 for Windows
• Microsoft Excel for Windows 95, versions 7.0, 7.0a
• Microsoft Visual Basic for Applications version 5.0
• Microsoft Office 2000 Developer
• Microsoft Excel 2000

SYMPTOMS

While running code that uses Automation to control Microsoft Excel, one of the following errors may occur:

With Microsoft Excel 97 or Excel 2000, you receive the error:

Run-time error '1004':
Method '<name of method>' of object '_Global' failed

Application-defined or object-defined error

Run-time error '-2147023174'
OLE Automation error

Run-time error '462':
The remote server machine does not exist or is unavailable.

CAUSE

Visual Basic has established a reference to Excel due to a line of code that calls an Excel object, method, or property without qualifying it with an Excel object variable. Visual Basic does not release this reference until you end the program. This errant reference interferes with automation code when the code is run more than once.

RESOLUTION

Modify the code so that each call to an Excel object, method, or property is qualified with the appropriate object variable.

STATUS

This behavior is by design.

MORE INFORMATION

To automate Microsoft Excel, you establish an object variable that usually refers to the Excel Application or Workbook object. Other object variables can then be set to refer to a Worksheet, a Range, or other objects in the Microsoft Excel object model. When you write code to use an Excel object, method, or property, you should always precede the call with the appropriate object variable. If you do not, Visual Basic establishes its own reference to Excel. This reference might cause problems when trying to run the automation code multiple times. Note that even if the line of code begins with the object variable, there may be a call to an Excel object, method, or property in the middle of the line of code that is not preceded with an object variable.

The following steps illustrate how to reproduce this problem, and how to correct it.

Steps to Reproduce Behavior

1. Start a new Standard EXE project in Visual Basic. Form1 is created by default.



2. Click References from the Project menu and check the Object Library for the version of Excel you intend to automate.



3. Place a CommandButton on Form1.



4. Copy the following code to the Code Window of Form1:




      Option Explicit

      Private Sub Command1_Click()
         Dim xlApp As Excel.Application
         Dim xlBook As Excel.Workbook
         Dim xlSheet As Excel.Worksheet
         Set xlApp = CreateObject("Excel.Application")
         Set xlBook = xlApp.Workbooks.Add
         Set xlSheet = xlBook.Worksheets("Sheet1")
         xlSheet.Range(Cells(1, 1), Cells(10, 2)).Value = "Hello"
         xlBook.Saved = True
         Set xlSheet = Nothing
         Set xlBook = Nothing
         xlApp.Quit
         Set xlApp = Nothing
      End Sub 

5. On the Run menu, click Start or press the F5 key to start the program.



6. Click the CommandButton. No error occurs. However, a reference to Excel has been created and has not been released.



7. Click the CommandButton again and note that you receive one of the errors previously described.
   
   NOTE: The error occurs because the code refers to the Cell's method without preceding the call with the xlSheet object variable.



8. Stop the project and change the following line:




xlSheet.Range(Cells(1,1),Cells(10,2)).Value = "Hello" 

to:

xlSheet.Range(xlSheet.Cells(1,1),xlSheet.Cells(10,2)).Value = "Hello" 

9. Run the program again. Note that you can run the code multiple times without error.

REFERENCES

For additional information, please see the following article in the Microsoft Knowledge Base:

Q167223 Microsoft Office 97 Automation Help File Available on MSL

Additional query words: activex automation OLE

Keywords          : kbinterop kbAutomation kbVBp kbVBp400 kbVBp500 kbVBp600 kbGrpDSO kbOffice2000 kbExcel97 kbVBA500 kbexcel2000 
Version           : WINDOWS:2000,4.0,5.0,6.0,7.0,7.0a,97; :
Platform          : WINDOWS 
Issue type        : kbprb 

Last Reviewed: June 8, 1999