Having problems with Paypal Subscriptions integration on my site.

Hi ,

I am having a problem with subscriptions using Paypal on my site.
Whenever the subscription is clicked the subscription is getting generated successfully using the apis with status as "Pending". The pending status can be moved to active only when the approval url generated in previous step is used to capture the amount requested. here I am getting this error "ngrlCaptcha.min.js:1

POST https://www.paypal.com/webapps/hermes/api/checkout/xxxxxxx/session/create 400 (Bad Request) " This step happens automatically and is no way integrated by me. I'm responsible for passing the creation of subscription and then using approval url to make the subscription active so no place to give a Bad Request. Any help would be greatly appreciated as the support has not replied on the case for a few days.