Cannot make a visible window modal

[MLNorton]

I have a Main Form that calls another form:
Form_LettersDisplay.ShowModal;
Form_Letters contains a DBGrid and a Close Button.
When I close the FormLetters Form I get the following message:
“Cannot make a visible window modal”

What causes this and what is the solution?

 

[DjangMan]

Show us the rest of the code around the call above.

 

[MLNorton]

Here is the entire code of the Form.

procedure TForm_LetterSent.FormActivate(Sender: TObject);
begin
Form_Main.RadioButton_LetterSent.Checked := false;
Form_Main.ADOTable1.Filter := '(MemLetter<>''-'') and (MemLetter <>''Sent'')';
Form_Main.ADOTable1.Filtered := true;
end;

procedure TForm_LetterSent.DBGrid1CellClick(Column: TColumn);
begin
Form_Main.ADOTable1.edit;
Form_Main.ADOTable1.FieldByName('MemLetter').AsString := 'Sent';
Form_Main.ADOTable1.post;
end;

procedure TForm_LetterSent.Button_CloseClick(Sender: TObject);
begin
Close;
end;

 

[DjangMan]

Show me the code that calls the window above.

 

[frank77]

rather than calling 'Close' you should do

ModalResult := mrCancel;

which will close the form.

(you could also set the ModalResult property of the button to mrCancel and then you wouldn't need the event handler)