Clock.currTime

[Kent via Digitalmars-d-learn]

I am reading the book 《D Cookbook》
In Page 36，this code can't be complied:

auto filtered =  filter!((a) => Clock.currTime() -
a.timeLastModified >> 14.days)(sorted);

"sorted"'s type is DirEntry[].

The errors :
Error	1	Error:
'currTime(cast(immutable(TimeZone))opCall()).opBinary(a.timeLastModified())'
is not of integral type, it is a Duration	

I don't know what's the problem?