vb编程中的类型不匹配咋解决

通过调用过程Average求数组的平均值，请装入该文件。使得程序运行后，在四个文本框中各输入一个整数，然后单击命令按钮，即可求出数组的平均值，并在窗体上显示出来.代码如下：

Option Base 1
Private Function average(a() As Integer) As Single
Dim start As Integer, finish As Integer
Dim i%, sum%
sum = 0
start = LBound(a)
finish = UBound(a)
For i = start To finish
sum = sum + a(i)
Next
average = sum / finish

End Function

Private Sub Command1_Click()
Dim arr1()
Dim arr2(4) As Integer
arr1(4) = Array(Val(Text1.Text), Val(Text2.Text), _
Val(Text1.Text), Val(Text2.Text))
For i = 1 To 4
arr2(i) = CInt(arr1(i))
Next
m = average(arr2(i))
Print m
End sub

为啥运行时系统提示“类型不匹配”

给sum赋值可能会出错，其不是Integer型，楼上的说的也是一方面~