QB Issue Resolution:

From the home page, click Create (+) > Invoice.
Make sure Online Payment is set to On.
Enter the invoice information.
Click Send.
Review the invoice in the Send email window. Tip: You can add additional information to the subject line and body of the email, if needed.
Select the Online Payment types that you would like your customer to pay with.
Click Send.

Details
Answer ID 5903
Products QuickBooks Online Simple Start (H)
QuickBooks Online Essentials (H)
QuickBooks Online Plus (H)
Categories Merchant Account Service
Date Created 08/09/2013 01:09 PM
Date Updated 12/27/2013 03:27 PM
Allow Crawling? Yes

Resolution for Issue 'Send a payment-enabled online invoice.' available: Yes (Solved).
Source: Intuit Community forum.

Send a payment-enabled online invoice.: this issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the issue yourself by looking for a resolution described below. If it is a complex issue or you are unable to solve the issue, you may contact us by clicking here or by using other support options.

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