Can't delete pictures with card reader?

Ok so i have a nikon d3100 and a pny 16gb class 10 sd card. When i try and use my card reader i can't delete any of the pictures. However when i use a usb cable and connect it to my camera i'm able to delete pics. Any ideas on why this is?

Are you sure you don't have the little clip on the sd card in the lock position?

Deleting image files is one sure way to cause card corruption

You need to place the memory card back in your camera and use the format feature on your camera

Look on page 21 of your user manual

David is correct. If you want to destroy your memory card that'll do it. Format the card in the camera. Follow the instructions in the book. Then, after every upload, format the card in the camera - every time.

If you are using the camera's software, then maybe it's looking for the camera's indentification in the USB connection.since it's not there, deleting may be blocked. There should be a setting to work around that.

If you are using My Computer or Finder then it doesn't make sense. These are the programs you should be using to do file management in your computer.

Yes, deleting files can corrupt data in the card. The best way to delete files is to copy everything to your computer, delete in the computer, format the card, copy back what you want to keep. Better yet, don't copy back. Burn to a CD and keep in a safe place. If you want to show off your pictures, use the computer.