INNO TUTORIAL - Using Unicode and ANSI Versions of INNO Setup

[seventhorama]

i have a problem

the patcher cant automatically detect the game installation folder

i put this in [Setup] section

[Setup]
AppName={#MyAppName}
AppVerName={#MyAppVersion}
AppPublisher={#MyAppPublisher}
AppPublisherURL={#MyAppURL}
AppSupportURL={#MyAppURL}
AppUpdatesURL={#MyAppURL}
DefaultDirName={app}\
DefaultGroupName={#MyAppName}
InfoBeforeFile=ReadMe.txt
OutputDir=E:\Installer
OutputBaseFilename=setup
Compression=none
DiskSpanning=yes
SlicesPerDisk=3
DiskSliceSize=1400000000

when i run it, it shows this error

"internal error: an attempt was made to expand the "app" constant before it was initialized"

do i need something? like registry section or something?

about the patcher, i need it separated from original installer. this one is kind of old games that have 2 disk and needed disk 2 to do the patch, so i get some files in the game installation folder that changes and put them in some folder.

then i try to make this patcher automatically detects the game installation folder and move needed files to replace the old files. and i need it to run silently (without user need to browse game installation folder). is it possible? where do i put silent parameter for this installer?