Object reference not set to an instance of an object in asp.

Question

this is my code...

-------------------- 

if (!fupImage.HasFile)

{

// File was sent

string stdid = Session["StdId"].ToString();

int length = fupImage.PostedFile.ContentLength;

if (length > 500 * 1024)

{

Response.Write("Ur image is too large");

}

else

{

byte[] pic = new byte[length];

//HttpPostedFile img = fupImage.PostedFile; img.InputStream.Read(pic, 0, length);

fupImage.PostedFile.InputStream.Read(pic, 0, length);

string res = std.StudentImageUpload(stdid, pic);

Response.Redirect("Dashboard.aspx");

}

}

else

{

// No file

}

this is my class function

-----------------------------

public string StudentImageUpload(string stdid,byte[] pic)

{

try

{

GetConnect();

SqlCommand cmd = new SqlCommand("insert into Std_Photo(StdId,Phto) values(@stdid,@photo)", SqlCon);

cmd.Parameters.AddWithValue("@stdid",stdid);

cmd.Parameters.Add("@photo", SqlDbType.Binary).Value=pic;

string res = cmd.ExecuteNonQuery().ToString();

GetClosed();

return res;

}

catch (Exception ex)

{

throw ex;

}

}

--------------------------------

my problem is  , executing time this line  int length = fupImage.PostedFile.ContentLength;  

got error for  Object reference not set to an instance of an object in asp.... how to solve this problem.?

 Thanks in advnce.