AutoCAD .NET :: How To Add Xrefs To Drawing

I am having an issue with adding xrefs to drawings.  The way I have this setup is the user inputs information and the number of sheets.  This then sets up a sheet set with the information and then for each value for the number of sheets the user gets a dialog askign for a number, name, and description for that sheet.

so if the user puts in 5 as the number of sheets, the user gets that dialog 5 times.

also I have a dialog that asks the user if they are adding xrefs to the sheets, if they answer yes then it adds the xrefs to each sheet that is created (this is where I have an issue).

This works perfect for the first sheet that is added, how ever after you fill in the information and submit for the second sheet autocad gives a fatal exception error and closes. not sure if I am missing on turning something off, closing, or stoping something before the next sheet is created.

here is the code I have at this point:

'checks to see if the dialog was yes
If xrefd.DialogResult = Windows.Forms.DialogResult.Yes Then 'shows the dialog efd.ShowDialog() 'shows the dialog pfd.ShowDialog() 'runs for each value in total sheets
For i As Integer = 1 To info.TotalSheetNum.Value 'shows the dialog sheetinfo.ShowDialog() 'checks to see if the sheet number is 1 If sheetinfo.SheetNum.Text = "1"
Then 'sets the sheet set default values SetSheetSetDefaults(ssdb, info.NameTxt.Text,
"Description",

[Code]....