What is the effect of a special instruction in a sexual assault case where the evidence does not "point unerringly to the guilt of the accused"?

Even an accurate statement of the law may be erroneous as an instruction if it is likely to mislead or misdirect a jury upon an issue vital to the defense and where the evidence does not "point unerringly to the guilt of the person accused...." (People v. Oden (1987) 193 Cal.App.3d 1675, 1682, 239 Cal.Rptr. 232.) In the instant case, the special instruction may have been accurate for the facts in Mijares from which it was adopted, but was misleading when applied to the facts here.