Error code P2002 DPF (DIESEL PARTICULATE FILTER)

Hi kindly help i imported an xtrail diesel NT 31 which came with a check engine once it arrived we did service and then checked errors as the check engine light was on ,an error of DPF appeared on the diagnostic machine ,the technician tried to do a regeneration to clear the code but it was not successful he cleared the error ,after which i drove around for 30kms before the check engine light came back on kindly assist on what should be done as that is really stressing me out please i have been using nissan all my life first time am having this issue though previously i was on petrol models