Connor Maguire from Boho was told despite the fact that his mother was accompanying him, he would be unable to go into the main function room because he was under 18.
Angered, his mother, Patricia, says there was no mention of an age restriction in posters and newspaper advertisements promoting the event.
"I have been to other concerts for Nathan before," she said, "I was at one in Bundoran and there were children as young as six there. I thought it was lovely to have your family together for it. It's a country dance night. Connor was going to be with me the whole time, I certainly wasn't going to allow him to drink.
"I wouldn't have brought him if I had known there there would be an age restriction. I wouldn't have put him through the disappointment. He was sorely disappointed.
"I spoke to a receptionist about it who said they didn't see a problem with it. But when the manager came, he said no.
"Nathan's manager said he would have allowed him in.
"I had two options: I had to bring him back out home or leave him in the foyer. I wasn't going to just leave him there, that would be so unfair, but I had brought other ones with me so I left Connor home and came back in again because I would have to pick them up anyway."
Patricia says her son has become a fan of Country star Nathan since the release of his latest single, Wagon Wheel.
His story does have a happy ending however: as a goodwill gesture, Nathan's management have offered Connor two tickets to see him perform at the Ardhowen in September, as well as the chance to have a picture taken with the singing sensation.
David Morrison, General Manager of the Killyhevlin, said the hotel has strict guidelines to adhere to.
"Whenever we do a non-food function or formal we always work on the basis that under 18-year-olds are not allowed in the main bar area of the function room," he explained, "This is working within the guidelines set down by the PSNI. For example, if we have a school formal, access is allowed to the main room, but the bar is in the foyer and it is strictly ID or no access to the bar.
"That wasn't an option on Wednesday night because of the huge crowds attending. I could not take responsibility for that individual being in the main function room.
"I'm afraid we just have to work within the legislation that is clearly set out for us. I cannot comment on what other establishments do or do not do.
"If there is an issue with the fact that no age restriction was mentioned in the advertisement, we didn't place the advertisement for the event, it was Nathan Carter's management. We have no control over what they put in the ad.
"I can understand that the child was disappointed, but we tried to do our best to facilitate and allow him access to the foyer without any issues potentially arising, but that offer wasn't taken up."