splitter string/char different behavior

[SrMordred]

writeln( "a.b.c".splitter('.').dropBack(1) ); //compiles ok
writeln( "a.b.c".splitter(".").dropBack(1) );

//error:
Error: template std.range.dropBack cannot deduce function from 
argument types !()(Result, int), candidates are:
(...)

Hm.. can someone explain whats going on?