vb中一个小错误该怎样改正呢
Option ExplicitOption Base 1
Private Sub Command1_Click()
Dim s$, pos%, j%, k%, a%(), i%
s = Text1
For i = 1 To 3
For j = 1 To 3
k = 0
pos = pos + 1
Do While Mid(s, pos, 1) <> "" And pos <= Len(s)
pos = pos + 1
k = k + 1
Loop
a(i, j) = Mid(s, pos - k, k)
Text2 = Text2 & CStr(a(i, j)) & ""
Next j
Text2 = Text2 & vbCrLf
Next i
End Sub
运行程序时红颜色的这句话,即a(i, j) = Mid(s, pos - k, k)总是提示“类型不匹配”,该如何改正呢,谢谢各位盟友了,我是南京农大学生,邮箱wsl1475548009@谢谢了。