System.InvalidCastException Error

        Me.lblDateFrom.Text = Me.calFrom.SelectedDate.ToShortDateString()
  Me.lblDateTo.Text = Me.calT.SelectedDate.ToShortDateString()
  strAllCC = "CEUReportByDates.aspx?PKey=" + strAllCC & "ToDate = '" + lblDateFrom.Text.ToString + "'FromDate = '" & +lblDateTo.Text.ToString & "'"
System.InvalidCastException was unhandled by user code
  Message="Conversion from string "7/6/2009" to type 'Double' is not valid."
  Source="Microsoft.VisualBasic"
  StackTrace:
       at Microsoft.VisualBasic.CompilerServices.Conversions.ToDouble(String Value, NumberFormatInfo NumberFormat)
       at Microsoft.VisualBasic.CompilerServices.Conversions.ToDouble(String Value)
 &nbs ...