Low income but still being asked to pay class 4 ni on my self assessment

I’ve just tried to file my 22-23 self assessment . I am in a partnership and split 50-50 . Our pre tax profits are well below the threshold . However when I do the calculations it’s says I still have to pay £1500 ! How do I get an exemption

Hi Netik123 Kerr,
We cannot comment on any form of calculation/example or scenario of this Forum, whether fact or fiction.
We will require to access your tax record to provide an answer to your question.  Please see 
Self Assessment: general enquiries.
Please allow 72 hours for us to receive your submitted Self Assessment return and then contact us for an explanation.
Thank you.