Teenagers do not understand why they are being given the chance to vote in the referendum but then denied a say in the subsequent parliamentary elections, according to an electoral administrator.
The one-off chance to help settle the constitutional future of Scotland and the UK next year is being extended to 16 and 17-year-olds through legislation at the Scottish Parliament.
While some parties want to lower the limit for all elections, it did not appear in the Conservative-Liberal Democrat coalition agreement at Westminster.
It means that some 16-year-olds may be able to vote in the 2014 referendum but, assuming a No vote, not the 2015 general election or the 2016 Holyrood election. There is also a European Parliament election next May.
The issue was raised by Patrick Harvie, a Green MSP on the Referendum Bill Committee, which is investigating the franchise.
"That could be pretty dispiriting, and disillusionment could set in," he said.
Kate Crawford, chair of the Scotland and Northern Ireland branch of the Association of Electoral Administrators, said young people already worry that politicians do not engage with them.
"What we're trying to do is explain to them that they will be voting in this one and you won't be voting in the next one. There is this confusion but we're trying to get the message over to them that the referendum is possibly a one-off but something they should be aware of," she said.
"They are not happy at being given the franchise in one and not in the other. They don't understand why that's happening. I think it's a huge education problem."