trouble assigning pads

so i just recently got a mpc500 and im having trouble assigning samples to the pads i want. sometimes it will let me and the other times it ask me "replace" and when i hit do it nothing happens and when it doesn't say replace it works fine. its getting pretty frustrating now so if anyone has any ideas or suggestions i would greatly appreciate it.

Replace means you already have the sample loaded. If you are having trouble try putting all of the samples you want in a single folder. Load the folder then go to program mode (SHift+6) and assign the samples there. Make sure you have the samples named in a way so you will know which is which.

Replace means that you have a sample of the same name already loaded, not necessarily the same sample.