In installation file it show the changes on catalog/admin/customers.php as follows .
But when you do that there is an extra } on the page and it become a reason to not complete " case 'deleteconfirm': " part and it doesn't work.

Replace:

$processed = true;

with:

$processed = true;
// +Country-State Selector
} else if ($refresh == 'true') {
$cInfo = new objectInfo($HTTP_POST_VARS);
}
// -Country-State Selector



So that change the part on top with the part down below.Now it works.

Replace:

$processed = true;
}

with:

$processed = true;
// +Country-State Selector
} else if ($refresh == 'true') {
$cInfo = new objectInfo($HTTP_POST_VARS);
}
// -Country-State Selector

No file.

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