In most cases, you will have multiple insurance policies. Accordingly, if a claim is not covered (or not fully covered) under one policy, you must not overlook the possibility it is covered by other policies.
However, be aware that if there is overlapping coverage, the extent of each insurance company's duty to contribute toward the loss is one of the most frequently litigated issues in business insurance claims. In this litigation, insurance companies are pitted against each other, with you (the insured) as an adversary of each company. And, don't expect any insurance company to voluntarily admit that it has a duty to contribute or even that the claim is covered under its policy.
This is why it is critical to know the scope of coverage of each policy, how to make timely claims under each policy and how to demand enforcement of the policy provisions.