Same Transaction Completion Issues in PayPal Sandbox
Could someone tell me/us the what the solution to this issue is? I've been beating myself up over this for a while now and my client is getting anxious. I'm pretty sure I've got every thing set up as per the instructions in "Using the PayPal Sandbox to test transactions", but I keep getting the ""We're sorry Your transaction could not be completed" message and I haven't been able to find anything specific to this in the forums.
I'm setting up to use PayPal Express.