No Transactions Showing In PayPal Sandbox

I am using the PayPal Sandbox to test out my PS2 site. After adding a product to my cart, I then click Checkout and the PayPal button to "complete the transaction", which takes me to the PayPal Sandbox login screen. I then login using the information I used to establish the Sandbox account. Then I select Test Accounts, select one of the test accounts and login to it after clicking the "Enter Sandbox Test Site" button. But in the "My Transactions" window there are no transactions listed.

Key WAGlobal settings:
$WAGLOBAL_Gateway = 1;
$WAGLOBAL_Test_Mode = false;
$WAGLOBAL_Paypal_Sandbox = "true";

NOTE: In case it may have some bearing, I did not first create a User via the Register process within PS2 before trying to "purchase" a product. Not sure that it required since I was never prompted to do so.

Does anyone have ideas on how I can resolve or troubleshoot this? Thanks in advance.