Well, reading setup script and find there are some typos Under [Registry], the .omod one should be Root: HKCR; Subkey: .omod; ValueType: string; ValueName: ; ValueData: OMOD_File_Type; Flags: uninsdeletekey; Tasks: associateOmodFiles Root: HKCR; Subkey: OMOD_File_Type; ValueType: string; ValueName: ; ValueData: Oblivion Mod Archive; Flags: uninsdeletekey; Tasks: associateOmodFiles Root: HKCR; Subkey: OMOD_File_Type\DefaultIcon; ValueType: string; ValueName: ; ValueData: {app}\{#MyExeName},0; Tasks: associateOmodFiles Root: HKCR; Subkey: OMOD_File_Type\shell\open\command; ValueType: string; ValueName: ; ValueData: """{app}\{#MyExeName}"" ""%1"""; Tasks: associateOmodFiles not “Tasks: associateFomodFiles”. :)