Absence depends on coverage
A missing entry matters only in relation to the record's purpose and completeness. If a book tracks paid visitors, it may omit staff or deliveries. If pages are missing, a blank search result may reflect missing coverage. Before treating absence as evidence that something did not happen, establish what the record would normally contain under the circumstances described by the case.
Worked example: the unlisted guest
A character's name is absent from a guest register, but an interview says they visited the building. The register may record overnight stays rather than every daytime visitor. Those statements can coexist. To make the absence significant, you would need evidence that this type of visit should have generated an entry and that the relevant part of the register survives.
Use a conditional conclusion
Phrase the inference explicitly: if all visits of this kind were recorded here, the missing entry would count against the claim. Then check whether the file supports that condition. Somatry's records may offer useful omissions, but a blank is not a universal answer. Making the expectation visible lets you distinguish an informative absence from a document that was never designed to capture the action you are trying to reconstruct.