I am trying to add a purchase transaction to a credit card in the credit card register using the NEW button. Not working.

Hi there, rstoc9.

Thank you for visiting the QuickBooks Community and for providing detailed information about your concern. I'll share details on how entries in reconciliation work in QuickBooks Online. Then, I'll ensure you can reconcile your credit card data smoothly.

One of the possible reasons why there's an entry appears on the reconciliation page but is not in the register could be the said transaction is deleted in the program. Since you already tried to add a transaction, please make sure that the entry you attempted to enter is assigned under the credit card account. Otherwise, I suggest creating a credit card expense in QuickBooks so you can match this to the existing one.

Here's how to create expenses:

1. Click the + New. Then, select Expense.
2. In the Payee field, select the vendor. 
3. In the Payment account field, select the credit card account you used to pay for the expense.
4. In the Payment date field, enter the date for the expense.
5. From the Payment method field, select how you paid for the expense.
6. In the Category details section, enter the expense info.
7. Fill in the other necessary field.
8. Click Save and close.

Once done, you can now match the expense you've created above to the downloaded transaction from your bank. You can refer to this article to see the steps on how to perform the process: Categorize and match online bank transactions in QuickBooks Online.

Then, you may click this artilcle to view detailed instructions on how you can reconcile your accounts to avoid discrepancies: Reconcile an account in QuickBooks Online.

Lastly, you may refer to this artilce to see different guidelines that help you fix any reconciliation issues: Learn the reconcile workflow in QuickBooks.

Feel free to comment below if you still have questions or concerns about managing reconciliation. I'm more than happy to assist you, rstoc9. Take care and have a good one!