The link you have used to enter the PayPal system is invalid. Please review the

I created a Paypal subcription button. Set payment in sandbox test. I enable IPN it paypal test account and configure Simple Membership plugin follow your document. But I got this message “The link you have used to enter the PayPal system is invalid. Please review the link and try again.” when click on Subscription button. I tried using live account with live mode but still get this message.
This is button form
<form method=”post” action=”https://www.sandbox.paypal.com/cgi-bin/webscr”><input type=”hidden” value=”_xclick-subscriptions” name=”cmd”><input type=”hidden” value=”utf-8″ name=”charset”><input type=”hidden” value=”TipsandTricks_SP” name=”bn”><input type=”hidden” value=”sample@inbusiness.no” name=”business”><input type=”hidden” value=”NOK” name=”currency_code”><input type=”hidden” value=”3332″ name=”item_number”><input type=”hidden” value=”5 Years Membership” name=”item_name”><input type=”hidden” value=”1″ name=”a3″><input type=”hidden” value=”1″ name=”p3″><input type=”hidden” value=”D” name=”t3″><input type=”hidden” value=”1″ name=”sra”><input type=”hidden” value=”1″ name=”src”><input type=”hidden” value=”60″ name=”srt”><input type=”hidden” value=”1″ name=”no_shipping”><input type=”hidden” value=”http://unisonelektro.inbusinessclients.no/?swpm_process_ipn=1&#8243; name=”notify_url”><input type=”hidden” value=”http://unisonelektro.inbusinessclients.no/membership-login/&#8221; name=”return”><input type=”hidden” value=”http://unisonelektro.inbusinessclients.no&#8221; name=”cancel_return”><input type=”hidden” value=”subsc_ref=2&user_ip=115.79.62.159″ name=”custom”><input type=”submit” value=”5 Years subscription” class=”swpm-subscription-button-submit”></form>`
`
It works if I use ‘Paypal Buy Now’ button type.
Please help me to fix it.
Thanks in advance.