It looks like you're likely using a non-public or certificate with a newer root certificate. If you're going to use the certificate in question, you will need to import the root certificate so that the device trusts it. I believe you can do this with an MDM solution like Mobile Secure or Afaria.
Unfortunately, I think you're in the wrong SCN space where we have limited expertise in this area. It looks like the following SCN space would be a better place for questions about SAP Business One mobile apps:
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