LTpowerCAD wont allow selection of ADP2303-5 Buck controller?

[Faringdon]

Hi,
We are trying to set up LTpowerCAD with a ADP2303-5 based buck converter for 12V to 5V and 0.5A output.
We want to use an inductor of 6.8uH, and an output capacitor of 56uF, Aluminium poly.
However, the LTpower CAD program wont allow this, it  keeps selecting  a different controller which we don’t want.  The program also runs very slowly, ( but this might be because i only have 4MB of RAM in my laptop?)

Do you know how to do this?