asp.net - PayPal IPN Sandbox response always INVALID -
i'm trying implement paypals ipn on website in asp.net using c#. using sample code given paypal found here: https://cms.paypal.com/cms_content/gb/en_gb/files/developer/ipn_asp_net_c.txt i have enabled ipn on account url of ipn on site. url used in code can see in link above sandox url paypal testing. i using ipn simulator , it's giving me "ipn sent response" on website displays invalid every time. i have tried displaying strrequest string in label , shows me "&cmd=_notify-validate" without quotes. thought meant add part on rest of returned data paypal. here button: this button i'm using <script src="paypal-button.min.js?merchant=myemail" data-button="buynow" data-name="name" data-quantity="1" data-amount="00.50" data-currency="gbp" data-shipping="0"