marketpress with chained payment configuration

Hello Evrybody,

I 'm facing to a problem to configure my marketpress chained paiement ... I 've tried a lot a things but there is always a prb ... so I will try to explain my configuration :

Ok ... :
- I've 3 paypal (sandbox) accounts ... 2 pro accounts + 1 buyer account to make test ...
- multisite configuration of wordpress (last version)
- marketpress (pro version) enabled (last version).

first step :
I configure network marketpress in network dashboard :
Limit Global Widgets/Shortcodes To Main Blog? -> Yes
Enable Global Shopping Cart? -> Yes
----
only permission to PayPal Chained Payments (for subsite)
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in paypal chained payment box, I enter a fees percentage, email of main paypal pro account, API Username (Sandbox), API Password (Sandbox) and Signature (Sandbox).

ok ... now :
step 2 :
I create a subsite (with of course marketpress enabled) and in the shop configuration (payment subfolder), I enter :
the email adress of my secondpaypro account ....

ok let try to a test ....

And finally I reach to a php errror (sometimes with different configuration to a paypal error -> ooopss - error ...) during payment.

So what's wrong with that ?

thanks a lot for your help

Fulgence

(I granted support for wpmu dev teamà