Please ensure that:
1. You are clicking on the correct assessment year form16 link.
2. You are using the compatible version of browsers before sharing the data (Internet Explorer 8 and above, Google Chrome 17 and above, Mozilla Firefox 11 and above, etc.)
3. If you are using Internet Explorer, then you should also check the security setting if set to High. Please make it to Medium. Goto Tools >> Internet Options >> Security.
If you get an error like failed upload (due to incorrect PAN or not able to read, etc.), then there is some error in the link in your form16. You have to proceed and enter the details manually. Alternatively, you can send us the form16 and we will upload the data from backend.