I am using `Paypal Website Standard` integration with `Asp.Net` and my problem is even after payment is successful, paypal is not returning me to my `thank-you.aspx` page. I have already set `return-url` in code as 

```
sbForm.Append("<input type=\"hidden\" name=\"return\" value=\"" + successUrl + "\">");

```

means, I have created form mark-up using `Code-Behind`. Success url is absolute reachable (I can copy `url` and paste in browser, it works). I have my `sand-box` settings as below:

1. Profile -> Selling Tools
2. Under `Selling Online` -> Website Payment Preferences
3. Auto Return: On
4. Return URL: `http://mywebsite/thank-you.aspx`
5. Payment Data Transfer: Off
6. PayPal Account Optional:On
7. Contact Telephone:Off (PayPal recommends this option)
8. Support giropay and bank transfer payments:No

However it return to cancel page without fail if I cancel payment.

**Edit**
Taking reference if [this](https://stackoverflow.com/questions/9338653/return-url-in-paypal-website-payments), I set `PayPal Account Optional:Off` but no luck.

**Edit**
When I click the link after payment success message on `Paypal`'s success page, I can go back and debug but it not returning any `QueryString` with the key name `tx` which results always `Fail\n` response.