1608: unable to create installdriver instance, return code: -2147467262 Windows 7 Instaling Sage Line50

you must try to uninstall the iss engine. Here the information from Flexera

The following options have been known to resolve this error message in the majority of cases:

    Reinstall the InstallScript engine by running the "isscriptx.msi" file located in the following location, where x is the version of InstallShield being used:

    <InstallShield Installation Location>\Redist\Language Independent\i386

    Example: The InstallShield 11.5 InstallScript engine is called "isscript1150.msi".
    Upgrade to InstallShield 12 or later.  These latest versions replace IDriver.exe with ISSetup.dll which will avoid this error entirely.  More information on the latest version available can be found at our Support page.

    Delete the folder <PROGRAMFILES>\Common Files\InstallShield\Driver, and run the InstallShield setup again to recreate this folder.

    Manually register the file "IDriver.exe" using the following command line:

        <PROGRAMFILES>\Common Files\InstallShield\Driver\<VERSION>\Intel 32\IDriver.exe /REGSERVER

    <VERSION> contains the version of InstallShield that is installed.
    Reset the DCOM permissions by following these steps:

        Launch the utility DCOMConfig by typing "dcomcnfg" in the Windows Run dialog.

        Select the Default Security tab.

        Click the Edit Default button in the Default Access Permissions section.

        Make sure you choose Allow Access permissions.

        Click OK in the utility, and re-run the setup.

    Empty all temporary folders. The specific temporary folders for a machine can be determined by accessing the DOS prompt and typing "set". Note the values listed for "TEMP" and "TMP", and delete all files in those locations.

    Make sure no other applications, including utilities such as virus scanners, are running in the background. Close all running applications and utilities, and launch the InstallShield setup again.

    If this occurs on a Windows 98 machine, install Microsoft DCOM98 from the link below, and re-run the setup:

        http://www.microsoft.com/com/dcom/dcom98/download.asp

    Make sure you have full administrative rights for that particular system.

    Reinstall the operating system, as this behavior has been known to occur when an environment has been corrupted.


Additional Information
      

If the error message also includes a negative number, such as "-2147467262", more information on this error code may be found by inserting the following InstallScript code into your script:

    MessageBox( FormatMessage( -2147467262 ), 0 );

This code translates the error code into meaningful text, which may assist in narrowing down the source of the problem.

Note: Some error codes do not contain meaningful text, and therefore the MessageBox may appear blank in these rare situations.

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the only one that worked