Script Task - Am I Leaving Any Resources Open?

I've got a service that waits for a file to drop and then calls a ssis package that then gets a date from the first line of the file, sets it to a variable, then imports the rest of the file using the flat file import through a data flow task.

Occasionally the script task fails with this error message:

The script threw an exception: Access to the path 'C:pathflatfile.txt' is denied.

Here is the code of my script:
Public Sub Main() ' ' Add your code here ' Dim vars As Variables Dts.VariableDispenser.LockOneForRead("User::FullFilePath", vars) Dim filepath As String = vars("FullFilePath").Value.ToString() vars.Unlock() Dim file As File Dim reader As StreamReader reader = file.OpenText(filepath) Dim line As String line = reader.ReadLine() reader.Close() 'MsgBox(line.Substring(29)) Dim asofdate As String asofdate = line.Substring(29, 5) asofdate = asofdate + "20" + line.Substring(34) 'MsgBox(asofdate) Dim writeVars As Variables Dts.VariableDispenser.LockOneForWrite("User::AsOfDate", writeVars) writeVars(0).Value = asofdate 'MsgBox("done") writeVars.Unlock() Dts.TaskResult = Dts.Results.Success End Sub
Does anyone see anything that I'm not. I believe i'm closing all necessary resources and streams. Does anyone have suggestions.

Thank you very much in advance.