1. Try to log in at www.diasend.com. If you can't log in there either, you are probably using an incorrect username or password. Click here
2. If you succeed to log in at www.diasend.com, but can't validate the upload with the same credentials, the problem is most likely due to the following:
During the installation process of diasend® Uploader you are required to select location (country of residence).
You may have registered your diasend® Uploader on the wrong server. To solve the issue, log into your account, go to the “Tools” tab, and download Uploader again (no need to uninstall the previous version from your computer). Reinstall diasend® Uploader and make sure you select the appropriate server location (the Uploader server location needs to coincide with the location of your username).