VB必选参数错误

xionglvxiang

Option Explicit
Private Sub subcomputeArea(length As Single, thewidth As Single)
    iblarea.Caption = Val(length) * Val(thewidth)
   
End Sub

Private Sub CmdResult_Click()
'On Error Resume Next
Call subcomputeArea(txtlength, txtwidth)
End Sub
运行到 Call subcomputeArea(txtlength, txtwidth)就出现必选参数错误