Ошибка при работе с матрицей "Subscript out of range" - VB

Private Sub cmd_start_Click()
    Dim x(4) As Single, y(7) As Single, S As Single, z() As Single, task1 As Single, task2 As Byte, task3 As Single, h_file As Byte, x_list1, y_list1, n
    h_file = FreeFile
    Randomize (Timer)
    Open ("C:\test\task.txt") For Output As #h_file
        Print #h_file, "Г‡Г*Г*Г·ГҐГ*ГЁГї Г¬Г*Г±Г±ГЁГўГ* x(i)"
        For i = 0 To 3
            x(i) = Int((Rnd * 100) - (Rnd * 100))
            list_output1.AddItem (x(i))
            Print #h_file, x(i)
        Next i
        Print #h_file, " Г‡Г*Г*Г·ГҐГ*ГЁГї Г¬Г*Г±Г±ГЁГўГ* y(j)"
        For j = 0 To 6
            y(j) = Int((Rnd * 10) - (Rnd * 10))
            list_output2.AddItem (y(j))
            Print #h_file, y(j)
        Next j
    Close #h_file
    ReDim z(list_output1.ListCount, list_output2.ListCount)
    For i = 0 To list_output1.ListCount - 1
        x_list1 = list_output1.List(i)
        For j = 0 To list_output2.ListCount - 1
            y_list1 = list_output2.List(j)
            list_output3.AddItem (z(x_list1, y_list1))
        Next j
    Next i
End Sub

Error 9: Subscript out of range

list_output3.AddItem (z(x_list1, y_list1))