Wrong db ticket?

i had mistakenly buy db ticket to frankfurt hauptbahnhoof am main instead of to flughafen. is it ok? when i arrived at hbf will they check again for the ticket and what happen if they found out that my journey end at hbf instead of flughafen? i bougth a dauer spezial ticket so i can't change it.

no, i've checked the detail. first it will stop at hauptbahnhoff for 10 minutes and then go to flughbahnhoff. it comes from leipzig

You'll have to buy a ticket for the extra distance between Frankfurt Hauptbahnhof and the airport if you travel from east to west. Other trains go to airport first and then stop at central station, but if it's the other way around, you have to cover the extra fare.
Normally, they check tickets between all stops. If you take a local train between Hauptbahnhof and airport, you might want t buy a ticket, because tickets are not sold in all local trains, and if you're caught you have to pay a fine of 40 Euros.

If you go by ICE or IC, you have two option: buy the ticket in advance. That's the cheaper version.

Option two: buy the ticket in the train. They'll charge you an additional fee for buying on the train, but if you're lucky the Schaffner won't make it through to your compartment by the time the train reaches the Airport and you don't have to pay. Of course that's sort of cheating, but you were willing to buy a ticket, after all. ;P

The train stop first at the Airport and than at the Hauptbahnhof. So what you need to do is just get out by the stop "Airport-Flughafen". Now you don't need to do anything with your ticket.

just go downstairs to the subway. you can catch one to the flughafen for a couple of euros. i think its the 3rd stop, if memory serves me well...

idk

If you go to the Hauptbahnhof first you can go ahead and get the ticket there for the Airport. Or, you'll ask the controller if you can pay on the train. However, it won't be possible for you to go all the way to the airport with this ticket!