VB 求知道

在调试程序时，Print #4,str这句时出现提示说：错误54，文件模式错误，这个你知道是怎么回事么

补充一下源代码：
Dim i As Integer,j As Integer,z As Double,v As Double,w As Double,str As String


Private Sub Command1_Click()

Open"F:\regression\dem_huabei_project90.asc"For Input As #1

Open"F:\regression\dem_huabei1_x90.asc"For Input As #2

Open"F:\regression\dem_huabei1_y90.asc"For Input As #3

Open"F:\regression\wheatmean.asc"For Input As #4

DO While Not EOF(1)

str = ""

For i = 1 To 13898

Input #1,z

Input #2,w

Input #3,v

If z>0 Then
 
z = -14.7534 * v + 2.103308 * w + 0.001688 * z + 840.7928 

End If

str = str & z & ""

Next i

Print #4,str

Loop

Close

End Sub

把 Open"F:\regression\wheatmean.asc"For Input As #4

改为
Open"F:\regression\wheatmean.asc"For Output As #4

你要输出肯定得指定为输出才行吧。