Can't use components on mainform from usersession

Hello,

Why I can't use components which are on IWMainform from usersession unit?

I have IWMainform which is mainfrm.pas and mainfrm.dfm. Then I place IWLabel on IWMainform.

Then I open Usersession unit and I create procedure:

uses mainfrm;

Procedure IWUsersession.BLA;
begin
  IWMainform.IWLabel1.caption:='blabla';   &t&t&t Here i got error Undeclared identifier 'IWMainform' ??
end;

I use latest version 16.0.9