Using innosetup for the setup procedure, I need to run a file after setup, depending on 32bit or 64 bit OS. I tried a few flags to check if the OS is 64 bit, but Innosetup seems to ignore those:

[Code]
function IsX64: Boolean;
begin
  Result := (ProcessorArchitecture = paX64);
end;

[Files]
; MsSql client:
Source: "..\Resources\SQLRuntimeFiles\sqlncli.msi"; DestDir: "{tmp}"; Components: CompleteClient; Check: not IsX64
Source: "..\Resources\SQLRuntimeFiles\sqlncli_x64.msi"; DestDir: "{tmp}"; DestName: "sqlncli.msi"; Components: CompleteClient; Check: IsX64

[Run]
Filename: {sys}\msiexec.exe; Parameters: /i {tmp}\sqlncli.msi; WorkingDir: {tmp}; StatusMsg: Installing SQL Server Native Client Drivers.; Flags: runascurrentuser;

It looks like it ignores the check and always copies both files. So when running the resulting setup.exe on a 32bit OS it gives the error message that it is not supported. What am I missing here?