Charm just isn't quite brave enough to come and get fed.

Notice the nice piggie house - but watch for this window design with large pigs they can get stuck.

When you first get your guinea pigs it is best to leave them alone as much as possible for the first couple of days. It is very tempting to keep picking them up and showing them to people but this is very stressful for them when they are in a new environment so please resist this until they have settled in. 

Make sure that each guinea pig has a nice house to hide in. Otherwise when they are startled the more dominant piggie will kick the other one out of the box and this can cause fights particularly amongst males. If possible don't disturb your pet when he is in his box as this will make them feel more secure. It is sometimes necessary to catch them by tipping over the box but do this as little as possible in the early days. 

Feed your guinea pigs at the same time every day. They will soon learn to assoicate the sounds of feeding with something nice happening. Ours squeak when they hear rustling and/or the frige opening. Also have times a couple of times a day when you give them treats. 

At first you may have to just put a treat outside the door of the nest box and move away but over time you should be able to get a guinea pig to take it from your hand. This is the most difficult part of the process and it is worth persevering. I spent a lot of time at this stage with Charm. I had to have a rule that if he didn't come and get it in a reasonable period of time I take it away again. This is because he had learnt that I would eventually give up and leave it and wouldn't take it. 

Once you have a guinea pig feeding from your hand it is often quite a quick process to get them to come further and further out of the box and eventually come to the edge of the cage to be fed. Before long your guinea pig will be standing ready for a treat. It is absolutely essential that you don't use a treat to catch the guinea pig at this point as it will stop them trusting you. Once they get to trust you really well you will be able to pick them up. As mentioned above both Truffle and Smudge will come over and be picked up now. 

Source: TGP