HL2 ep 1 roller mine to alyx -1 reply

I can't figure out how to get alyx to take the roller mine, I have dropped it, put in on console, etc..but she continues to tell me to get her a roller mine. help !!!

Get the roller Mines that are falling out a shout through a force field, bring one back to her and using the Gravity Gun, hold it close to her.

I have tried that countless times, but nothing ever happens. Can't understand why it doesn't work. Thanks