Payment Gateway Integrations in PHP

[sanjay]

I have integrate Square Payment Gateway in PHP. I use E-commecre API. First I test my API on Localhost and used sandbox value for it.

When I submit Credit card Information for test it is 

• Card Number 4532 7597 3454 5858
• Card CVV 111
• Card Expiration (Any time in the future)
• Card Postal Code (94103 )

It give a message in alert box

 Nonce received! CBASEJhgvF0gmJx39P_eE4P2vNsgAQ {"card_brand":"VISA","last_4":"5858","exp_month":5,"exp_year":2025,"billing_postal_code":"94103"}

 and then redirect to process-card.php path. and then it give response-

Caught exception!
Response body:

NULL

Response headers:

NULL

So, I want to know that why it gives -response body NULL

I use my sandbox information, that is

Application Id-: sandbox-sq0idp-GkdLuMxecal1NYbs_9MVHA

Acces Token:- sandbox-sq0atb-EbHNhdFi2Okaob4-GihlbQ

My real Application id is -: sq0idp-GkdLuMxecal1NYbs_9MVHA

Suugest me, Where is problem.

Thanks in advance.