Error when installing extension

[surknight]

Installation: Abantecart 1.1.4 on localhost, Windows Vista 64bit platform
Extension attempted: The free Google checkout payment extension

Here's what I got when I plugged the installation key from the extension marketplace into the 'install extension' dialogue:
Fatal error: Class 'Atargz' not found in C:\xampp\htdocs\abantecart_surknight\public_html\core\lib\package_manager.php on line 141

I saw on a similar topic that a suggested reason for this error was missing files from the original abantecart distribution, but I don't think that's the case. I extracted everything from public_html into the abantecart_surknight directory and the core\lib directory has all 52 of the files in the original zip (including the targz.php file) so if there's something missing somewhere it's not in that particular directory. Is there a master listing somewhere of what files are supposed to be in the entire installation that I can compare what I have installed to?

Thanks.

[abantecart]

Possibly there is no TAR GZIP support on your windows computer or php.

Also, check the error log and see if you have error  "Error: Could not load library tardz"

Check that you have file core/lib/targz.php present

[surknight]

Possibly there is no TAR GZIP support on your windows computer or php.

Also, check the error log and see if you have error  "Error: Could not load library tardz"

Check that you have file core/lib/targz.php present

I've installed 7zip, ran it as admin and associated .tar, .gz, and .tgz files for all users, so I do have TAR GZIP support on the computer. Didn't solve the problem from within the Abantecart interface though.

core/lib/targz.php file is definitely present and accounted for.

I do have an error in the log, but not the one you mention. This is it: "error:  AbanteCart core v.1.1.4 Class 'Atargz' not found in C:\xampp\htdocs\abantecart_surknight\public_html\core\lib\package_manager.php on line 141"

I checked PHPinfo (PHP version 5.4.7) and I have: "Registered PHP Streams php, file, glob, data, http, ftp, zip, compress.zlib, compress.bzip2, https, ftps, phar"
I'm assuming that .tar gzip should be appearing in there, so how do I activate/register it? I already tried uncommenting the following lines in C:\xampp\apache\conf\httpd.conf :

    #AddType application/x-gzip .tgz
    #AddEncoding x-compress .Z
    #AddEncoding x-gzip .gz .tgz

Didn't help though - still getting the same error about "Class 'Atargz'" above.

[impeesa]

I refer to C:\xampp\htdocs\qcodestore\core\lib\targz.php
I found on top targz.php script
<?
change with
<?php

and error in AbanteCart v1.1.5 file usually forget to change <? with <?php 
so please check another file in AbanteCart if this happen. I hope can solve it. 

Thanks