Buy limit order errors. Can someone explain why?

When I want to submit a buy limit order via the API, I receive the following message: ‘reject_reason’: ‘sell order exists, buy limit price should be less than existing sell limit price’. I understand what it means, but how am I supposed to trade if I can’t buy for a lower price than I was selling previously? This should mean that I can only buy for more and more, which is not desired by me. Is this fixable?