"Illegal characters in path" Exception ?

[M-Dayyan]

Hi. I'm using LINQ to SQL.
I wanna create a database with LINQ but the following exception has occurred : Illegal characters in path.

My snippet code :

public static string DBFolder = Application.StartupPath + "\\SQL\\";   
//the path is equal with "D:\My Works\C#\Win Form\Reza Restaurant\RezaRestaurant\bin\Release\SQL"
private void MainForm_Load(object sender, EventArgs e)
{
    if (!Directory.Exists(StaticVariables.DBFolder))
        Directory.CreateDirectory(StaticVariables.DBFolder);
    using (RezaRestaurant.SQL.DataClasses1DataContext dbc = new RezaRestaurant.SQL.DataClasses1DataContext())
    {
        if (!File.Exists(StaticVariables.DBFolder + dbc.Mapping.DatabaseName + ".mdf") && !dbc.DatabaseExists())
        {
            RezaRestaurant.SQL.DataClasses1DataContext db = new RezaRestaurant.SQL.DataClasses1DataContext(StaticVariables.DBFolder + dbc.Mapping.DatabaseName + ".mdf", dbc.Mapping.MappingSource);
            db.CreateDatabase();//Exception
        }
    }
} 

Stack Trace :

at System.IO.Path.CheckInvalidPathChars(String path)
   at System.IO.Path.NormalizePathFast(String path, Boolean fullCheck)
   at System.IO.Path.NormalizePath(String path, Boolean fullCheck)
   at System.IO.Path.GetFullPathInternal(String path)
   at System.IO.Path.GetFullPath(String path)
   at System.Data.Linq.SqlClient.SqlProvider.System.Data.Linq.Provider.IProvider.CreateDatabase()
   at System.Data.Linq.DataContext.CreateDatabase()
   at RezaRestaurant.MainForm.MainForm_Load(Object sender, EventArgs e) in D:\My Works\C#\Win Form\Reza Restaurant\RezaRestaurant\Forms\MainForm.cs:line 364 

Could you please guide me ? Thanks.