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I have a DLL add-in for Excel that adds an API for another program I have. Add-in had an installer package and after install I can't find it in the Excel add-ins list. I have a suspicion that it is a 32-bit addin that may be causing the problem. Is there a way to check if the DLL is 32-bit? Even if it is 32-bit should it cause a problem to run on 64-bit Excel? Help!

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Unless you are 100% sure the add-on is able to support a 64-bit installation of Excel 2010 I would just remove the add-on in question. The alternative is to remove the 64-bit version of Excel 2010 and install the 32-bit version instead. – Ramhound Aug 31 '12 at 16:43
Does this add-in purport to work with Excel 2010 at all? – Ƭᴇcʜιᴇ007 Aug 31 '12 at 16:57
Yea i know it works for other people, though I've only asked one person what bit version and they were using 32 – riotburn Aug 31 '12 at 17:46

Is there a way to check if the DLL is 32-bit?

You can refer to the question, How can I find out if a given program is 64 or 32 bit version?, for that. That will work for DLLs and libraries, too.

Even if it is 32-bit should it cause a problem to run on 64-bit Excel?

Yes. 32-bit programs cannot load a 64-bit library, and vise-versa. So if you have a 32-bit Add In that you need to use, then you need to install the 32-bit Excel.

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How do I use it check the dll? Can't figure it out. – riotburn Aug 31 '12 at 17:25
@riotburn - Follow the directions....The answer for the linked question explains how to use the tool. Just do file myfile.dll instead of file myfile.exe just common sense. – Ramhound Aug 31 '12 at 17:32
doesn't work just get 'file' is not recognized as an internal or external command. This is after cd to the directory containing the dll and then typing file my.dll – riotburn Aug 31 '12 at 17:48
If the addin was explicitly compiled for use on 32-bit systems then your out of luck. Typically 32-bit software is fine running on 64-bit, but only if it was compiled as such. – Lee Harrison Aug 31 '12 at 17:59

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