Det kan muligvis skyldes forskellige rekonstitutionsmetoder, de valgte intervaller mellem injektioner, de injicerede muskler og marginale forskelle mellem toksinets virkning, der skyldes den anvendte biologiske testprocedure eller sekundært manglende respons.
The possible reasons are different techniques of reconstitution, the chosen injection intervals, the injected muscles and marginally varying toxin activity resulting from the biological testing procedure employed or secondary non-response.