IF ELSE syntax required for this formula !

Hi Experts,

Please help me on this

[Age (days)] = IF [Clearing date] is not empty then [Clearing date] ELSE [Last data of the reporting period]) - [Net Due Date]

How can I write in bex formula with the above values??

Please help me with syntax.

Note : net due date, clearing date & last data for reporting period are charcterics in the cube.

Thanks

surendra