The 27-year-old has been one of Charlton's most consistent players over the past couple of years but has scored just four times in 79 appearances and has yet to find the net this season.
He had a golden opportunity to open his account in Sunday's goalless draw with Wigan but skied his shot over the crossbar.
"I'm still kicking myself at the chance," he said.
"I tried to get my head over it, I've been working on that one-on-one with (football advisor) Keith Peacock in training.
"It is frustrating because I try to get into those positions where I can try and score and I feel I should be scoring more.
"So when I get those chances I should convert them because at this standard you don't get many as clear cut as that."