I've had an elusive error # 49: "Bad DLL calling convention."  Couldn't
trace it to its offending code line as usual.

A Google search turned up a helpful thread from October 1999 in this
newsgroup, which I paste in below.

I followed the advice of Wojtek Korycki (below), which didn't work.
However, when I did a decompile (using command line switch) then recompiled,
it did work.

So, problem fixed, this time, by doing a decompile, then recompiling.

I am running Access 2002 using Access 2002 file format, under Windows XP
Professional.

Hope this will be helpful for someone else.

Mark Hammer
Lake Oswego, Oregon

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

Subject: Access200 - Error 49: "Bad DLL calling..."

Newsgroups: microsoft.public.access.modulesdaovba

View this article only

Date: 1999/10/08

From time to time I get error 49: "Bad DLL calling convention" for no

apparent reason. I figured that if I comment out the code where the error

occurs, compile, then uncomment that code, and recompile again - that fixes

the problem (at least for a while).

Any idea why the error 49 occurs and how to avoid it?

(another Access bug?)

Woj

Message 2 in thread

Subject: Re: Access200 - Error 49: "Bad DLL calling..."

Newsgroups: microsoft.public.access.modulesdaovba

View this article only

Date: 1999/10/08

I have seeen this fairly regularly.... it is coming from

inside VBE. I do not know of a workaround, but I have seen

it in both Excel and Access.

--

MichKa

can you identify any specific circumstances leading to the
error? (opening a certain form, running certain code, ...)

The error you are receiving  error # 49: "Bad DLL calling convention" is
often caused by incorrectly omitting or including the ByVal keyword
from the Declare statement. This error can also be caused if the wrong
parameters are passed.

Text from Article:Q142138

Bad DLL calling convention (Error 49)
-------------------------------------

Your program is calling a routine in a dynamic-link library (DLL) that
either is
being passed the wrong type or number of arguments or does not use the
Pascal
calling convention. Make sure that the arguments passed to the DLL routine
exactly match the arguments expected by the routine. If the DLL routine
expects
arguments by value, then make sure ByVal is specified for those arguments
in the
declaration for the routine.

I hope that this is helpful.

Thank you for working with Microsoft Developer Support for Access,

Jeff MacLeod, MCP
Microsoft Technical Support        

Of course, this posting wouldnt be complete without a nice, juicy
disclaimer from our lawyers:? This posting is provided AS IS
with no warranties, and confers no rights. You assume all risk
for your use. ? 2001 Microsoft Corporation. All rights reserved.

However Mark specifically stated "Couldn't trace it to its offending
code line as usual."  Surely if it was a declare statement problem the
VBA compiler would highlight the line of code in question.

Tony
--
Tony Toews, Microsoft Access MVP
   Please respond only in the newsgroups so that others can
read the entire thread of messages.
   Microsoft Access Links, Hints, Tips & Accounting Systems at
http://www.granite.ab.ca/accsmstr.htm

The fact that all you had to do is recompile would indicate that code did
not need to be changed in order to get it to work so, as Tony has pointed
out, an invalid declaration is not likely the cause in this case.

From the description of the issue, I would suspect that the VBA Project may
have become damaged and the recompile recreated the project. Access 2000
and 2002 have a significantly different storage mechanism for compiled code
than we used in Access 97 and before. In essence, what was saved in
individual locations is now all lumped together in the VBA Project,
affectionately referred to as the "blob," and can be quite large in size.
For a description of what has changed and why, please see article:

Q287603 - ACC2002: Saving Objects in DB Slower Than in Earlier Versions

    http://support.microsoft.com/support/kb/articles/q287/6/03.asp

If the VBA Project actually did get damaged, you may want to take a look at
the following article which describes how to minimize the risk of
corrupting the database file.

Q303528 - HOW TO: Keep a Jet 4.0 Database in Top Working Condition

    http://support.microsoft.com/support/kb/articles/q303/5/28.asp

I hope this helps! If you have additional questions on this topic, please
reply to this posting.

Regards, Frank Miller
Microsoft Support

This posting is provided AS IS with no warranties, and confers no rights.

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of our products including Microsoft " Most Valuable Professionals" - MVP's.
For more information please see
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Thanks for the clarifications.

Tony
--
Tony Toews, Microsoft Access MVP
   Please respond only in the newsgroups so that others can
read the entire thread of messages.
   Microsoft Access Links, Hints, Tips & Accounting Systems at
http://www.granite.ab.ca/accsmstr.htm