During Order Entry, you may receive a popup alert message telling you that one of the selected products cannot be sold with the selected payment method.  There are a couple of possibilities for why you may be receiving this error.

1) Verify that the payment method is allowed in the script settings for the given source you are using to enter an order.  To verify this, navigate to Company Data -> Advertising -> Source and filter for the DNIS/Source you were using when you received the error messgae. When you locate the source record in the list of sources, click on the hyperlink of the name of the Script associated to that DNIS to launch the Script Properties window. Click the Pay/Shipping tab and locate the the payment method you were selecting when you received the error.  If the payment method is already in the selected area, please see #2 below.  Otherwise, move the desired payment method from the "Available" area to the "Selected" area.  Save your script settings and try to re-enter the order and the error should be resolved. 

2) If your payment method is listed as an accepted method of payment on the script then the message is generally caused by a javascript error. This is usually indicated by a yellow shield with an exclamation point appearing in the bottom corner of your screen. To resolve this issue please try the following:

-a- Clear your cache in Internet Explorer.

-b- Lunch Internet Explorer, and using the Menu Bar, navigate to File -> New Session.

-c- Finally launch OLX from the new IE session by actually inputting the URL (no bookmarks or shortcuts).