I'm not sure based upon your question exactly which state has charged you with failing to register. That being said, failure to register as a sex offender can be a difficult case to prove in the state of florida. The reason is, the statute is written in such a way so as to provide an offender with the burden to register within a certain time limit upon arrival in a new place. If you're traveling by car across the state of florida, the statute does not require you to register in each and every area in which you pass thru. So, how does this relate to your case? Well, hopefully, you have not said much to the police. The crime of failure to register often times requires the confession of the sex offender in order to prove the case--or at least in order to forclose any possible 'other scenarios' such as what's described above.
These are tricky cases, and the police investigating are even worse. You MUST contact an attorney as soon as possible to discuss your options. You MUST NOT speak to anyone else, nor should family be discussing this case with anyone without first speaking with your attorney.