Captions in Inno Download Plugin

[User]

How can I change the captions of the page title and description of the IDP Wizard page?

I have tried with this but I get the Type mismatch compiler error.

[Code]
procedure CurPageChanged(CurPageID: Integer);
begin
if CurPageID = IDPForm.Page then begin
WizardForm.PageNameLabel.Caption :=
ExpandConstant('{cm:R_WizardReady}');
WizardForm.PageDescriptionLabel.Caption :=
ExpandConstant('{cm:R_ReadyLabel1}');
end;
end;

Sorry for the gramatical errors, I have a low level of English.