AppendText won't append to the next line in a text file / vb - vb.net

Question

I'm making a program that lets you add student info to an existing CSV text file but whenever I use append text it adds the new info to part of the last line and then a new line.
I want it to do this:
John Doe,29,Male
John Doe,29,Male
It does this instead:
John Doe,29,MaleJo
hn Doe,29,Male
Note: there isn't actually an empty line between each set of info, I just wanted it to be easy to read when I posted it here.
Here is the code for that section:
Dim swVar As IO.StreamWriter = IO.File.AppendText(frmMain.fileName)
swVar.WriteLine(txtName.Text & "," & txtAge.Text & "," & gender)
swVar.Close()
Any help would be appreciated, thanks!

Answer 1

A handy tool in VS2010 (and others) is snippets - right click Insert Snippets... - lots of code patterns for typical tasks. In your case here is a modified snippet:
Sub AddToFile(textToAdd As String, filePath As String)
My.Computer.FileSystem.WriteAllText(filePath, textToAdd, True)
End Sub
You may want to check/add a vbNewLine to the text being added since one is not automatically added as with WriteLine.
Not a direct reply to your stated problem, but an alternate method.

Answer 2

See if something like this works better:
IO.File.AppendText(frmMain.fileName, vbNewLine & txtName.Text & "," & txtAge.Text & "," & gender & vbNewLine)
AppendText will open write and close all in one operation so there's no need for a separate streamwriter. It also doesn't add newlines so those must be added separately
Unless of course you are doing a series of writes to the same file then something like this would probably be more appropriate:
Dim swVar As New IO.StreamWriter(frmMain.fileName, True)
'write your lines here
swVar.WriteLine(txtName.Text & "," & txtAge.Text & "," & gender)
swVar.Close()