Frequently Asked Questions
- How come I am not seeing my function show up in the workbook or Function Wizard?
- Most likely because you didn't load it. If you are running in the debugger, be sure to specify the full path to the Excel executable on your machine as the
Command
and "$(TargetPath)"
as Command Arguments
in
Properties|Configuration Properties|Debugging
.
- When I open my
.xll
file in Excel nothing happens. - You need to set macro security to low in order for Excel to register your functions and macros. For Excel 2003 and earlier, go to
Tools|Options...
and click on Macro Security...
in the
Security
tab. For Excel 2007 and later, from the Office Button click on
Excel Options
next to Exit Excel
on the bottom right. On the Trust Center tab click on
Trust Center Settings...
On the Macro Settings
tab choose
Enable all macros
.
- How do I get my add-in to load every time I start Excel?
- That is what the Excel
Add-in Manager is for.
- What is up with all those popups showing me errors and warnings?
- The xll add-in library provides three levels of alerts: error, warning, and information. Hit Alt-F8 and type
ALERT.FILTER
to control which of these you see.

Your choices are stored in the registry when you hit OK so they persist between Excel sessions. Hitting Cancel is equivalent to deselecting all alerts.
- Why am I seeing a message box claiming Register failed for: X, where X is the Excel name of one of my functions?
- You forgot to insert
#pragma XLLEXPORT
as the first line in the body of the corresponding C/C++ function.
- What can I do if
XLL.DOC
is not generating my help file? - Look in the Debug directory. You should see a folder with the same name as the xll you are building. In that you will find
.log
files. Look through them in alphabetical order for error messages.
- Why is
malloc()
failing while trying to allocate large amounts of memory? - You must compile with default char unsigned.
Properties|C/C++|Command Line|Additional Options: /J
- How come the last arguments in the constructor of
AddIn
end with an extra character? - It is a known feature that persists in the Excel 2010 SDK that the last character gets truncated.
- I'm using Vista/Windows 7 and can't veiw the Macrofun.hlp file.
- You need to install the Windows Help program. Just follow the directions
- When I call my add-in function from Excel it returns
#VALUE
. - This can occur when there is a mismatch between the C signature you specify in the second argument to
AddIn
and the true signature.