Joomla: 2.5.24
CB: 1.9.1
CbSubs: 3.0.0

I am using the paypal advanced gateway and have a Paypal business account with PayFlow (in Australia).

I have been working with Paypal tech support on this but so far they have not been able to solve it, so thought I would see if you have come across this before.
Paypal payments work fine and credit card payments are working in live mode, but when I put everything in test mode (CbSubs payment gateway and Paypal manager settings) and use a test credit card, the payment fails.

Initially I was getting the error message:
Some required information is missing or incorrect. Please correct the fields below and try again.
Error: Information entered incorrect. Try again.
I was using the test credit card number you supplied and various others supplied by paypal.

This morning I created a new sandbox personal account and used the credit card details from that with CSC=123. In Paypal Manager I also changed Show Confirmation Page to On My website and then back again to On a paypal hosted page. Either way, now, on return from payment I see no error message but the top half of my website is displayed in place of the Paypal iFrame (I am using Layout C). In the notifications in the back end I get the following message:
ERROR:Invalid merchant information: 10501-This transaction cannot be processed due to an invalid merchant configuration.
Raw data: $message_type="NOTIFICATION";
$requestdata=array (
'TYPE' => 'S',
'STATE' => 'SW',
'USER4' => 'S',
'ZIPTOSHIP' => '2087',
'ACCT' => '5975',
'EMAILTOSHIP' => 'annette@netsavvy.com.au',
'EMAIL' => 'annette@netsavvy.com.au',
'ADDRESSTOSHIP' => '53 Milham Cres',
'METHOD' => 'CC',
'SHIPTOCOUNTRY' => 'AU',
'TRANSTIME' => '2014-08-21 19:17:44',
'INVOICE' => '140835',
'STATETOSHIP' => 'SW',
'USER3' => 'S40-607-1',
'BILLTOZIP' => '2087',
'SHIPTOSTATE' => 'SW',
'BILLTOCITY' => 'Forestville',
'TAX' => '0.00',
'CARDTYPE' => '1',
'AVSDATA' => 'XXN',
'CITYTOSHIP' => 'Forestville',
'SECURETOKEN' => '8NYJjcgeWyUaWY3brWHsxagHY',
'INVNUM' => '140835',
'CITY' => 'Forestville',
'USER1' => '35',
'HOSTCODE' => '10501',
'BILLTOSTREET' => '53 Milham Cres',
'RESULT' => '5',
'TRXTYPE' => 'S',
'BILLTOEMAIL' => 'annette@netsavvy.com.au',
'USER2' => '607',
'BILLTOLASTNAME' => 'Spooner',
'BILLTONAME' => 'Annette Spooner',
'SHIPTOCITY' => 'Forestville',
'LASTNAME' => 'Spooner',
'TENDER' => 'CC',
'PNREF' => 'B11P6F7B5ABC',
'SHIPTOZIP' => '2087',
'BILLTOFIRSTNAME' => 'Annette',
'AMT' => '40.00',
'NAMETOSHIP' => 'Annette Spooner',
'ZIP' => '2087',
'BILLTOCOUNTRY' => 'AU',
'EXPDATE' => '0819',
'RESPMSG' => 'Invalid merchant information: 10501-This transaction cannot be processed due to an invalid merchant configuration.',
'COUNTRY' => 'AU',
'SHIPTOSTREET' => '53 Milham Cres',
'BILLTOSTATE' => 'SW',
'FIRSTNAME' => 'Annette',
'SECURETOKENID' => '53f6a6f1951cf',
'NAME' => 'Annette Spooner',
'COUNTRYTOSHIP' => 'AU',
'ADDRESS' => '53 Milham Cres',
);
$_GET=array (
'option' => 'com_comprofiler',
'task' => 'pluginclass',
'plugin' => 'cbpaidsubscriptions',
'cbpgacctno' => '3',
'result' => 'notify',
'format' => 'raw',
'Itemid' => NULL,
);
$_POST=array (
'TYPE' => 'S',
'STATE' => 'SW',
'USER4' => 'S',
'ZIPTOSHIP' => '2087',
'ACCT' => '5975',
'EMAILTOSHIP' => 'annette@netsavvy.com.au',
'EMAIL' => 'annette@netsavvy.com.au',
'ADDRESSTOSHIP' => '53 Milham Cres',
'METHOD' => 'CC',
'SHIPTOCOUNTRY' => 'AU',
'TRANSTIME' => '2014-08-21 19:17:44',
'INVOICE' => '140835',
'STATETOSHIP' => 'SW',
'USER3' => 'S40-607-1',
'BILLTOZIP' => '2087',
'SHIPTOSTATE' => 'SW',
'BILLTOCITY' => 'Forestville',
'TAX' => '0.00',
'CARDTYPE' => '1',
'AVSDATA' => 'XXN',
'CITYTOSHIP' => 'Forestville',
'SECURETOKEN' => '8NYJjcgeWyUaWY3brWHsxagHY',
'INVNUM' => '140835',
'CITY' => 'Forestville',
'USER1' => '35',
'HOSTCODE' => '10501',
'BILLTOSTREET' => '53 Milham Cres',
'RESULT' => '5',
'TRXTYPE' => 'S',
'BILLTOEMAIL' => 'annette@netsavvy.com.au',
'USER2' => '607',
'BILLTOLASTNAME' => 'Spooner',
'BILLTONAME' => 'Annette Spooner',
'SHIPTOCITY' => 'Forestville',
'LASTNAME' => 'Spooner',
'TENDER' => 'CC',
'PNREF' => 'B11P6F7B5ABC',
'SHIPTOZIP' => '2087',
'BILLTOFIRSTNAME' => 'Annette',
'AMT' => '40.00',
'NAMETOSHIP' => 'Annette Spooner',
'ZIP' => '2087',
'BILLTOCOUNTRY' => 'AU',
'EXPDATE' => '0819',
'RESPMSG' => 'Invalid merchant information: 10501-This transaction cannot be processed due to an invalid merchant configuration.',
'COUNTRY' => 'AU',
'SHIPTOSTREET' => '53 Milham Cres',
'BILLTOSTATE' => 'SW',
'FIRSTNAME' => 'Annette',
'SECURETOKENID' => '53f6a6f1951cf',
'NAME' => 'Annette Spooner',
'COUNTRYTOSHIP' => 'AU',
'ADDRESS' => '53 Milham Cres',
);

Do you have any suggestions?
Thanks.

I have resolved this problem. The sandbox test account had not been upgraded to pro, but the live account had, hence the difference.