Try it with different data.
In the above example you have 68 EA converted to 68 CS Cases.
But there is no standard coversion factor to say how many pieces are in case 1,12,..30 ?
( May be wrong on that point but don't think so ).
Try it with KG to LB .
You can't just take weight and convert it into volume unless you know density.However conversions between different weight measurements is possible since they have same dimension id value on T006
Or maybe your problem would be solved by using data on MARM. It has the conversion factors to convert between base unit of measure of a material and alternative unit of measures for a given material. So for a givem material if you are trying to convert MARD data you need bounce around via MARA & MARM too instead of off the shelf UoM conversion ability within HANA.