diff --git a/htdocs/public/payment/paymentok.php b/htdocs/public/payment/paymentok.php
index ec92989f031..389daafcd15 100644
--- a/htdocs/public/payment/paymentok.php
+++ b/htdocs/public/payment/paymentok.php
@@ -529,7 +529,7 @@ if ($ispaymentok)
 			}
 			else
 			{
-				$postactionmessages[] = 'Failed to get a valid value for "amount paid" or "payment type" to record the payment of subscription for member '.$tmptag['MEM'];
+				$postactionmessages[] = 'Failed to get a valid value for "amount paid" or "payment type" to record the payment of subscription for member '.$tmptag['MEM'].'. May be payment was already recorded.';
 				$ispostactionok = -1;
 			}
 		}
@@ -646,7 +646,7 @@ if ($ispaymentok)
 			}
 			else
 			{
-				$postactionmessages[] = 'Failed to get a valid value for "amount paid" ('.$FinalPaymentAmt.') or "payment type" ('.$paymentType.') to record the payment of invoice '.$tmptag['INV'];
+				$postactionmessages[] = 'Failed to get a valid value for "amount paid" ('.$FinalPaymentAmt.') or "payment type" ('.$paymentType.') to record the payment of invoice '.$tmptag['INV'].'. May be payment was already recorded.';
 				$ispostactionok = -1;
 			}
 		}