Amazon api product listing says 'could not connect to amazon', while replace 'com' with 'in' in aws_signed_request() function

I'm using Amazon API for product listing in my php(joomla) website.

Files included:

amazon_api_class.php

aws_signed_request.php

files download link

Im getting response when I use "com" as region

private function queryAmazon($parameters)
    {
    return aws_signed_request("com", $parameters, $this->public_key, $this->private_key, $this->associate_tag);
    }

When I replace "com" with "in", im getting error that "could not connect to amazon" and it returns empty value.

private function queryAmazon($parameters)
    {
    return aws_signed_request("in", $parameters, $this->public_key, $this->private_key, $this->associate_tag);
    }

I need to list the products from amazon.in not from amazon.com