[SOLVED] Transaction result:FAIL Error: 4020

Joomla! 1.5.26
CB 1.8
CBSubs 1.3.0 RC2

Having switched PDT (Payment Data Transfer) On for my PayPal gateway I got an error when processing a test subscription (A previous payment, with PDT off, worked fine):
"Sorry your payment has not been processed. Transaction result:FAIL Error: 4020. Please try again and notify system administrator.
No suitable basket found."

However the payment and auto-recurring subscription was processed.

I am at a loss to know how to proceed. Can I email you the notifications / IPN details so that you can advise me what to do?

Please check History Log to see what error occurred as it should provide you with the full error message.

In CBSubs' PayPal Gateway, I changed “PayPal Business (email or secure merchant ID)” & “PayPal Main receiver account (email) (if Business is different from your main account)” from web@nabo.org.uk to be the primary rather than the second PayPal default.
That dealt with the relevant errors shown on PayPal's IPN History.

However, when I repeated the test, both IPN messages reported Transaction Made. I had the same error message on my website on completion:
"Sorry your payment has not been processed. Transaction result:FAIL Error: 4020. Please try again and notify system administrator.
No suitable basket found."
On the CBSubs Notification Report, I had the following Notification Type: PDT notification not authenticating at payment gateway.
The Raw Result began FAIL and ended $_POST=array (
);
$transaction_info='FAIL
Error: 4020';
$PDT_RESULT=array (
0 => 'Error: 4020',
);

I don't want to post the full CBSubs Notification because I am unsure what would be insecure

Edited to add: Everything seems to have worked fine otherwise at CBSubs end: subscriptions, baskets, payments

Believe that means the identity token isn't correct. Please ensure you're completely configured the PayPal gateway correctly. As for configuration I recommend the below to avoid issues.

PayPal Business (email or secure merchant ID): Merchant ID
PayPal Main receiver account (email) (if Business is different from your main account): Email address marked as "Primary" in your PayPal account
Your PayPal Identity Token: Token provided by PayPal

Tends to work better in my tests when using the merchant id instead of using email address.

Repeated test with Merchant Id replacing email. Checked PayPal Identity Token correct.
>>>>Edited to say PayPal Identity Token INCORRECT after further checking!!!

Same error message on return to our website from Paypal:
Sorry your payment has not been processed. Transaction result:FAIL Error: 4020. Please try again and notify system administrator.
No suitable basket found.

All seems to be correct in CBSubs, as last time: Subscriptions, Baskets, Payments

3 Notifications(as last time):
16/04/12 19:51:30 IPN: Verified for single payment (seems OK)
16/04/12 19:51:25 IPN: Verified for recurring payment(seems OK)
16/04/12 19:51:14 PDT notification not authenticating at payment gateway FAIL

Notification details:

Notification Id: 10
IP Address: ***redacted***
Notification type: PDT notification not authenticating at payment gateway
Log date: 16/04/12 19:51:14
Username: Jones91000
Full name: Nathan Graham Jones
User Id: 1000

Other sections blank except for
Test Payment Notification: 0
Payment Basket: 0

Raw Result:
FAIL
Raw data: $_GET=array (
'plugin' => 'cbpaidsubscriptions',
'cbpgacctno' => '1',
'cbppdtback' => '***redacted***',
'cbpbasket' => '5',
'result' => 'success',
'cbpid' => '***redacted***',
'tx' => '***redacted***',
'st' => 'Completed',
'amt' => '15.00',
'cc' => 'GBP',
'cm' => '5',
'item_number' => '',
'sig' => '***redacted***',
'Itemid' => '239',
'option' => 'com_comprofiler',
'task' => 'pluginclass',
);
$_POST=array (
);
$transaction_info='FAIL
Error: 4020';
$PDT_RESULT=array (
0 => 'Error: 4020',
);


Where do I go from here, please, Kyle?

I re-checked the identity token and noted that the second character was a lower case w instead of an upper case W - how that could have happened given I used cut and paste, I don't know. But it did!
Having re-pasted the PayPal Identity Token, the transaction went through AND returned me to the correct page.
Thank you for your help.