有段自编程序想请编程高手来指导一下我这菜鸟！

问题描述：

我初学VB依例编了一段花瓣的程序，可是运行不出来！！！请纠错！
Private Sub Command1_Click()
Dim x As Single, y As Single
Dim a As Single, b As Single, c As Single
Dim i As Single, k As Single
pi = 3.14159
d = 4
Picture1.Scale (-15, 15)-(15, -15)
For a = 0 To 256 Step 80
For b = 0 To 256 Step 80
For c = 0 To 256 Step 80
For k = 5 To 30 Step 5
For i = 0 To 2.01 * pi Step pi \ 60
x = k * Cos(i * d) * Cos(i)
y = k * Cos(i * d) * Sin(i)
Picture1.PSet (x, y)
Next i
Next k
Next c
Next b
Next a
End Sub
错误大概应该在定义颜色的值a，b，c上因为如果去掉有关b,c的语句则可以运行！！真心求教！！

问题解答：

有段自编程序想请编程高手来指导一下我这菜鸟！这个旅游问答期待您的解答，请登录账号或关注微信公众号回答这个问题。