I have generated my keys for Sandbox and was trying to login and get a token generated. I am using my current ebay account that I have had for years and it says my User Name or password is wrong? It is not? I have double checked everything. I can not login to my account via Developer (Sandbox)? Any ideas?
Please make sure you are using your sandbox test account when you try to login which is prefixed by 'testuser_' Can you please try again and follow every step mentioned in this KB :