FREDERICKSBURG, VA (AP).- A group trying to build a national slavery museum in Virginia has missed a deadline to pay more than $215,000 in back taxes to the city of Fredericksburg. City Treasurer G. M. Haney says the National Slavery Museum missed Saturday’s deadline to pay taxes on 38 acres of land. Haney tells the Free Lance-Star (http://bit.ly/nblk7S ) the city’s law firm plans to place an advertisement about the sale of the land, valued at $7.6 million. Former Gov. L. Douglas Wilder spearheaded efforts to build the National Slavery Museum. Haney says neither Wilder nor the museum’s registered agent has contacted the city about the delinquent taxes.