You either use :
background-image: url("images/plaid.jpg");
background-repeat: no-repeat;
... or
background: transparent url("images/plaid.jpg") top left no-repeat;
... but definitively not
background-image: url("images/plaid.jpg") no-repeat;
EDIT : Demo at JSFIDDLE using absolute paths (in case you have troubles referring to your images with relative paths).