Test for specific array position?

Hi

I have a 2 dimensional array stored in sessions scope:

     <cfset Session.POarCart=#arrayNew(2)#>

and it can have as many as 7 elements (for example):

     Session.POarCart[1][1]

     Session.POarCart[1][2]

     Session.POarCart[1][3]

     Session.POarCart[1][4]

     Session.POarCart[1][5]

     Session.POarCart[1][6]

     Session.POarCart[1][7]

... however elements 6 and 7 (Session.POarCart[1][6] and Session.POarCart[1][7]) don't always get filled (or populated, or set, whatever the nomenclature....)

Does anyone know how to check if a specific array element "contains something"? "is not null"? "has length"? I can test that the array exists, and it does, but I don't know how to test for the exact position of the array.

My code is failing when I attempt to reference Session.POarCart[1][6] because it doesn't contain anything.

Anyone?

Thanks,

Rich