Crucial ballistix memory dual problem on prescott

[Meridius]

hi all i bought some of this
http://www.crucial.com/crucial/pvtcontent/memorytype.asp?memtype=Ballistix240-pinDIMM

but having problems using ti as dual channel memeory in the asus p5ad2 deluxe motheroard it will not boot or work but in single channal m,od eit works can anyone help me here

thanks