Using return and short-hand if in C#

Why wouldn't the following line of code work in a method?

return (count > 0) ? true : false;

It works perfectly fine if I do:

bool ret = (count > 0) ? true : false;
return ret;

Bonus Question: Is it really faster or more effective than the standard if statement?

bool ret = false;
if(count > 0)
    ret = true;
return ret;

Which one would you recommend?