(char* str) is not callable using argument types (string)

[Zaheer Ahmed via Digitalmars-d]

I am Developing and Operation System in D and when writing 
writeln("Zaheer"); function, I got an ERROR.
Error: function kernel.dwriteln (char* str) is not callable using 
argument types (string)
I also tried Casting.
I Developed OS in C and C++ but first time stuck in types.