An IPN transaction failed verification for this order after Paypal payment

I get "An IPN transaction failed verification for this order" error after every Paypal payment.

IPN coming like this:
Receiving IPN at URL for order 11.
Array
(
[mc_gross] => 100.00
[invoice] => 11-1
[protection_eligibility] => Ineligible
[item_number1] =>
[payer_id] => ANRHFCWJUK63Y
[tax] => 0.00
[payment_date] => 06:34:11 Feb 14, 2016 PST
[payment_status] => Completed
[charset] => windows-1252
[mc_shipping] => 0.00
[mc_handling] => 0.00
[first_name] => test
[mc_fee] => 4.20
[notify_version] => 3.8
[custom] =>
[payer_status] => verified
[business] => seller@****.com
[num_cart_items] => 1
[mc_handling1] => 0.00
[verify_sign] => AG3GVp.wDJ4dWGZRsyfOBr1DLPQYAvnHqYWZoGnUGaacx2MOgp6ZSYO5
[payer_email] => buyer@****.com
[mc_shipping1] => 0.00
[tax1] => 0.00
[txn_id] => 2K892764TU6503212
[payment_type] => instant
[last_name] => buyer
[item_name1] => Order 11 at Ubercart
[receiver_email] => seller@****.com
[payment_fee] => 4.20
[quantity1] => 1
[receiver_id] => SN5N3PBDL4Y6W
[txn_type] => cart
[mc_gross_1] => 100.00
[mc_currency] => USD
[residence_country] => US
[test_ipn] => 1
[transaction_subject] =>
[payment_gross] => 100.00
[ipn_track_id] => 992a364c4292c
)

And after that coming that error. Is that bug or some configuration mistake? Also Orders transaction ID is all the time Unknown.