Cannot Copy The Mdf File After Processing

I have a windows service that connects to a regular sql server 2005 database and basically bulk copies data into a SQL express database. Afterwards, I just want to copy the MDF file into a different directory. I keep getting the "Process cannot access file because it is being used by another process" error. I've tried changing the connection strings but nothing seems to work. I'm closing the connections in the code as well. Here is the code. Any thoughts or help would be appreciated. RefreshDB calls Sync 3 times and if all three calls are successful, it attempts to copy the database file to the specified location. This is where I get the error.

Public Function RefreshDB() As Boolean
Dim success As Boolean = True
Dim tables() As String = {"Job", "Equipment", "PMScheduled"}
For Each tableName As String In tables
If SyncTable(tableName) = False Then
success = False
Exit For
End If
Next
If success Then
'copy the new database to the target directory
Try
File.Copy(My.Settings.DBFilePath, My.Settings.TargetDirectory + "EMField.mdf")
Catch ex As Exception
My.Application.Log.WriteEntry(ex.Message + "(RefreshDB)", TraceEventType.Critical)
Return False
End Try
End If
Return success
End Function


Private Function SyncTable(ByVal tableName As String) As Boolean
Dim reader As SqlDataReader
Dim sourceViewName As String = String.Format("EMField{0}View", tableName)
Dim connectionString As String = My.Settings.EMFieldConnectionString
'insert the path to the database into the connectionstring
connectionString = connectionString.Replace("[DBFilePath]", My.Settings.DBFilePath)
Try
'clear the target table first
Using targetConnection As New SqlConnection(connectionString)
Using truncateCommand As New SqlCommand(String.Format("TRUNCATE TABLE {0}", tableName), targetConnection)
targetConnection.Open()
truncateCommand.ExecuteNonQuery()
targetConnection.Close()
End Using
End Using
'create a datareader from the source database
Using sourceConnection As New SqlConnection(My.Settings.EMLiteConnectionString)
Using readCommand As New SqlCommand(String.Format("SELECT * FROM {0}", sourceViewName), sourceConnection)
sourceConnection.Open()
reader = readCommand.ExecuteReader
BulkCopy(tableName, reader, connectionString)
reader.Close()
sourceConnection.Close()
End Using
End Using
Return True
Catch ex As SqlException
My.Application.Log.WriteEntry(ex.Message + "(sync)", TraceEventType.Critical)
Return False
End Try
End Function

Public Sub BulkCopy(ByVal tableName As String, ByRef reader As SqlDataReader, ByVal connectionString As String)
Try
'bulk copy from source to target database
Using bulkCopy As New SqlBulkCopy(connectionString)
bulkCopy.DestinationTableName = tableName
bulkCopy.WriteToServer(reader)
bulkCopy.Close()
End Using
Catch ex As SqlException
'throw exception back to calling sub
Throw ex
End Try
End Sub