It seems on the old computer, they've put it in a sample mode, and I can't transfer the photos to the new computer.
I don't know what this means. Could you explain further?
Well, I can't develop the photos on the old computer.
I copy them on a disc, go to install them on the Lightroom on the new computer, and Lightroom doesn't recognize them.
It states on the copies they are in raw, but lightroom won't put them into a new file in the library.
Does that explanation help?
No. Please give the exact complete unedited message. Also please explain exactly where (what step, what exact Lightroom command) in this process you are getting this message. Or show us a screen capture.
Installing Lightroom on a new computer involves installing the program itself like you normally would. It also involves copying the catalog and images from the old computer to the new one. The easiest way to make the transfer is to ensure that the path to your photos remains the same as it was on the old computer. However, if that isn't possible then here are the instructions on how to link the photos to the Lightroom catalog again on the new computer:
And here are some instructions outlining the process of moving Lightroom and your images to a new computer: