Labrador MP Yvonne Jones has issued an apology for failing to stand for a roll call during a vote in the House of Commons on Wednesday on a bill to create a national dementia strategy.

Her oversight was a costly one for Claude Gravelle, the Nickel Belt NDP MP who had been working on the bill for years.

Bill C-356 failed by a vote of 140-139.

During an interview Monday with Radio One's Labrador Morning, Jones said she "inadvertently" failed to stand up and register her vote when the roll call was being conducted.

I inadvertently missed one … and I feel terrible about it. - Liberal MP Yvonne Jones

Jones planned to support the bill, and her endorsement would have tied the vote and kept the debate alive.

A sharp rebuke

She said there was "no reason in particular" for her non-vote, "other than there were a lot of roll calls being done at the time."

So how is it possible she forgot to stand and vote?

Jones said the chronology in which MPs vote varies each time, and often depends on who proposes the bill. She said voting can begin on the government or opposition side, and your name is not called unless you stand.

Jones said there were five votes that day, and she thought she took part in each one.

"I inadvertently missed one … and I feel terrible about it," she said.

Her inaction drew a sharp rebuke from Gravelle.

"To forget to stand up and vote, you either have to be dead in your seat because everyone around you is standing up, behind you, beside you, in front of you," he said.

"For someone to say they forgot to stand up doesn't do it for me."

'Felt very bad'

Ryan Cleary, NDP MP for St. John's South-Mount Pearl, also criticized Jones, saying she missed an opportunity to help Canadians and their families coping with dementia.

Jones said she "felt very bad" for her oversight and called the Alzheimer Society of Newfoundland and Labrador to offer an apology.

"They know I've been a supporter of theirs for many years," she said.

She also shot back at Cleary for "going out on an edge" to make political hay of her non-vote.

Jones said Gravelle's motion is a private member's bill and, without the support of the governing Conservatives, is probably "not going to do very much at the end of the day."

"Basically, it's just showing your support for a cause, and I was certainly willing to do that," she said.

Where were the NDP?

Jones said if the NDP were so committed to the bill, they would have made sure all the party's MPs were in attendance for the vote.

"The one thing Ryan Cleary and the NDP have not answered for is why their own members didn't show up for the House of Commons that day and vote in support of their own motion," she said.

"I make mistakes like everyone else."