If all you did was stick the new drive in there that's perfectly normal, the 'key' that's on your old drive needs to be injected into the FW of the new drive before it will work like it's supposed to.
Since both drives are Samsung you have a couple options, depending..
1. If the old drive was just giving ya issues reading games the laser is all that probably needed to be replaced, so just swap the Logic boards in them, put yours in the new drive and that basically turns the new drive into your old drive. This will work provided the issue with your old drive wasn't something like a failed modchip install or ya bricked it trying to flash it or it's damaged in some other way on the actual board, that's gonna take a lot more work to get straightened out.
2. Dump your old drives FW and just flash it to the new drive, again provided your drive is in working order, but option 1 is the better way to go about this and you can since both drives are Samsung. Since they're both Samsung drives (FW version doesn't matter) you can do this and don't need to do just the key or any spoofing of the FW.