Indirect control logix

I am trying to do some indirect addressing in control logix 5000 and having no luck.
In PLC 5 I used to write it like this B3/[N10:0], if N10:0 was say 60 then Bit B3/60 would be true.
I cannot get this to work on control logix at all.
Any help would be most appreciated

Jules

Create tag B3 type BOOL[1000]
Create Tag INDEX type DINT

Address B3[INDEX]
If index=60 it will address B3[60]