请教使用控件ADODC问题，

   Z1 = Val(Text1(0)): Z2 = Val(Text1(1))
   If Check3 = 0 Then                                                         '自动计算切向变位系数
     sb = Z2 / Z1
     Adodc1.Visible = False
     Adodc1.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & App.Path & "\biao1.mdb;Persist Security Info=False"
     Adodc1.RecordSource = "select * from qx where A<=" & Z1 & " and B>=" & Z1 & " and C<=" & sb & " and D>=" & sb
     Set DataGrid1.DataSource = Adodc1
     Text1(8) = Adodc1.Recordset.Fields(1).Value
     Adodc1.Refresh
     DoEvents
   Else
     Xt = Val(Text1(8))                                                          '自定义切向变位系数
   End If
   访问数据文件，首次输入Z2=34,Z1=21，Text1(8)=0，但改变Z1=6时，计算一次Text1(8)却还是原来的0，正确答案是0.265，而我再计算一次，才能是0.265，为什么要计算二次才能得到正确的答案，我之前都好计算一次，现在不知道什么原因，都要计算二次。请帮忙看下