Why main form can't access to DataModule's images and actions when project is open in Delphi XE?

My Delphi XE application was fine till a couple of days and I can't figure out what is wrong. My project layout:

• Visual controls are on the main form
• Actions and image lists for those controls are on a data module

When I open my project, the main form doesn't have any image or actions associated to any of the controls, even though they should be. When I compile I get the error message: "Module 'winMain' links to module 'modGeneral' which cannot be found in the current project. Do you wish to remove/redirect the links to another module?".

The work around: close the main form after I've opened the project, then open the module in the IDE by double-clicking it in the project manager (yes, it is present in the current project), then re-open the main form: all my actions and images are now correctly displaye开发者_运维百科d.

What do you think, is that a known Delphi bug ? A problem with my project ?

Check your .dpr file. One way to reproduce your problem is to change the uses clause in it. Consider this example which works fine:

program Project1;

uses
  Forms,
  Unit1 in 'Unit1.pas' {Form1},
  Unit2 in 'Unit2.pas' {DataModule2: TDataModule};

{$R *.res}

begin
  Application.Initialize;
  Application.MainFormOnTaskbar := True;
  Application.CreateForm(TForm1, Form1);
  Application.CreateForm(TDataModule2, DataModule2);
  Application.Run;
end.

The icon in the Project Manager looks as usual for a module with a dfm:

If you remove the comment, or comment it out:

program Project1;

uses
  Forms,
  Unit1 in 'Unit1.pas' {Form1},
  Unit2 in 'Unit2.pas'; // {DataModule2: TDataModule};

{$R *.res}

begin
  Application.Initialize;
  Application.MainFormOnTaskbar := True;
  Application.CreateForm(TForm1, Form1);
  Application.CreateForm(TDataModule2, DataModule2);
  Application.Run;
end.

Here, the icon has changed:

...and you get the errors you describe. You need to close and reopen the project for your changes to take effect.

TOndrej's answer is complete and correct. I have just a small addition which I maybe should post as comment but I'm afraid it won't be noticeable. I faced with the described error after unit renaming and project file refactoring (actually I removed all the in and comments from uses section). I returned the required pattern in the uses section but I still got the error. My mistake was an alignment that I added to comments in uses section:

DMMain     in 'DMMain.pas'     {fdmMain    : TDataModule},
DMIndex    in 'DMIndex.pas'    {fdmIndex   : TDataModule},

Surprisingly it really matters. Removing the alignment

DMMain     in 'DMMain.pas'     {fdmMain: TDataModule},
DMIndex    in 'DMIndex.pas'    {fdmIndex: TDataModule},

fixed the error and I got things working.