CSS validation question

My CCS file has the following setup –

#contentleft ul li{
	background:transparent url("images/ul-bullet.gif") 0px 3px no-repeat; /* 0px = horizontal position for left, 6px = vertical position from top */
	margin: 0px 0px 0px 0px;
	padding: 0px 0px 0px 18px;
	}

But, I get the following CSS validation error from it.

207 #contentleft ul li Value Error : background Too many values or values are not recognized : transparent url("images/ul-bullet.gif") 0 3px no-repeat transparent url("images/ul-bullet.gif") 0 3px no-repeat

Does anyone know where the error lies?