Why Delphi says "Unit xxx compiled with a different version of yyy" if all my paths are correct?
First of all I would like to apologize for the question itself. I simply could not make anything better. Well, the question then follows with examples and detailed ...
I manually installed QuickReport Delphi 2006 from their sources. It is composed of two packages a "DesignTime" and a "RunTime".
My Delphi is configured to build the BPL files in "D:\BPL" and DCP files on "D:\DCP" for all packages compiled on my Delphi
The source code of QuickReport are in "D:\QuickReport" and their packages (design and runtime) are configured to save the compiled units (DCU) in the folder "D:\QuickReport\DCU." This was the only configuration done in the packages. Nothing is set up with different paths and, BPL and DCP files are placed correctly in the folders I've set up, as I mentioned earlier.
With these settings I was able to build and install QuickReport without problems (just a few compiler warnings, which I believe are normal). All QuickReport components appear in your palette in Delphi, which does not emit any error on start proving that the components are properly installed and all packages were found.
Now comes the test: I started a new win32 application, completely empty, just a blank form. Then it put a QuickReport component (TQuickRep). The first thing I noticed was that the unit "QuickRpt", which is automatically placed in the clause "uses" of the "interface" is underlined in red indicating that something is wrong.
When I perform a CTRL+ENTER in "QuickRpt" unit (uses clause), the Delphi finds the source file (.pas) correctly, which is in "D:\QuickReport" then I ran a BUILD ALL command and the following compilation error appeared:
[Pascal Fatal Error] Unit1.pas (7): F2051 Unit QuickRpt was compiled with a different version of QRExpr.TQREvElement
That's it!!!
This error is only happening with Quick Report. I have other third-party components installed using the same configuration as the paths and they all work properly.
Answer
Finally I was able to solve this problem. @RRUZ and another friend gave me the tip: An lost QuickRpt.dcu file on my system. There were a QuickRpt.res file also. I found them, but the place was very improbable to me: The delphi LIB folder!!!
Well, i have some clues about this bizarre thing.
Until Delphi 7, the QuickReport was shipped together with the IDE however, it was disabled by default. On that Delphi version, all we need to do is to register the bpl to gain full access to QuickReport!
On Delphi 2006, the QuickReport is not part of IDE and there are no BPL to register, however the guys at Borland forgotten to remove all files from the old QuickReport. The Delphi Lib Folder is one of the first folders to be checked on Delphi start, so, if there are old files there, new files on another place would be never compiled, generating the annoying error!
This problem may be present on Delphi 2005 too.