Why couldn't Voldermort kill Harry Potter with Lucius Malfoy's wand?

I just finished watching the film Harry Potter and the Death Hallows: Part 1. I don't know how the series will conclude as I haven't read the books. Without spoiling anything, why couldn't Voldermort kill Harry Potter with Lucius Malfoy's wand in the the beginning of the film? If I need to continue watching to find out, then I'll accept that as an answer. Thank you, kindly.