急需大神求解！本人菜鸟刚接触vb。

Public Xn As Single, Yn As Single
Public X0 As Single, Y0 As Single
Public Xt As Single, Yt As Single
Public n As Double

Xn = n(Xt - X0) + X0
Yn = n (Yt - Y0) + Y0
为什么这样编译提示缺少数组？而下面这样就ok。
Xn = n * (Xt - X0) + X0
Yn = n * (Yt - Y0) + Y0