fORMAT eXCEPTION

Hi
I am continuously getting the error:

Exception Details: System.FormatException: Input string was not in a correct format.

Source Error:

Line 57: {
Line 58: Connection.Open() ;
Line 59: ThreadResult = ThreadCommand.ExecuteNonQuery() ;
Line 60: }
Line 61:

in the following part of the code :

protected void PostClick(object sender,EventArgs e)
{
SqlConnection Connection ;
SqlCommand ThreadCommand ;
SqlCommand GetThreadCommand ;
SqlCommand MessageCommand ;
SqlDataReader ThreadReader ;
string InsertThread,InsertMessage ;
string GetThread,Message ;
long ThreadID ;
int ThreadResult ;
Connection = new SqlConnection("server=HT; Integrated Security= SSPI; Database=Forums");
Feedback.Text = "" ;
InsertThread = "Insert Into Threads(ThreadName,TopicId) VALUES(@.ThreadName,@.TopicId)" ;
ThreadCommand = new SqlCommand(InsertThread, Connection) ;
ThreadCommand.Parameters.Add(new SqlParameter("@.ThreadName", SqlDbType.VarChar,50)) ;
ThreadCommand.Parameters.Add(new SqlParameter("@.TopicId", System.Data.SqlDbType.Int));
ThreadCommand.Parameters["@.ThreadName"].Value = ThreadText.Text ;
ThreadCommand.Parameters["@.TopicId"].Value = Request.QueryString["TopicId"] ;
try
{
Connection.Open() ;
ThreadResult = ThreadCommand.ExecuteNonQuery() ;
}
catch (System.Data.SqlClient.SqlException excp)
{
if (excp.Errors[0].Number == -105121349)
{
Feedback.Text = "<font color=red>*** There is already a thread with the name"+ThreadText.Text+". Please choose a different name and click Post.</font><br><br>" ;
}
else
{
Feedback.Text = "<font color=red>*** "+excp.Errors[0].Message +"<br><br>" ;
}
}

I would be very grateful for any suggestions.I expect the problem is here:

ThreadCommand.Parameters["@.TopicId"].Value = Request.QueryString["TopicId"] ;

Perhaps Request.QueryString["TopicId"] is null, or not a value that can be converted into a number? Debug the application and check this value, or alternately, do a Response.Write("TopicID: " + Request.QueryString["TopicId"] );|||Hi
Yes Mr.Douglas you are right. but the problem lies in this statement only in this page. Actually i think its in the following line in the other page :

<a href="http://links.10026.com/?link=threads.aspx?TopicId=<%=Request.QueryString["TopicId"]%>&TopicName= <%=Request.QueryString["TopicName"]%>"
Actually on printing TopicId, i noticed its '1' (with comma) instead of being just 1 due to the courtesy of above line. Can you please tell me how can i remove the comma thats being appended. Thanks a lot|||I presume when you say comma, you really mean the single quotes ' and ' and if so, change to this:

=<%=String.Trim(Request.QueryString["TopicId"],"'".ToCharArray()%
The best bet would be to determine why, on the previous page, it is putting the single quotes in.|||Yes you are right , i can use the trim method but Mr. Douglas why is the following statement attaching a comma.

<%=Request.QueryString["TopicId"]%
in

<a href="http://links.10026.com/?link=threads.aspx?TopicId=
<%=Request.QueryString["TopicId"]%>
&TopicName=<%=Request.QueryString["TopicName"]%>"
Thanks a lot and Mr. Douglas i would like you advise on a designing tool . Which one do u use since yesterday i was trying to do things with Html Table but thats a HeadAche and i can't even arrange the data the way i like.|||I have no idea what the value of Request.QueryString["TopicID"] is, but my guess is that somehow, it has the apostrophes.

I tend to use a mix of tables and Cascading Style sheets, but honestly, my page design skills are less than perfect.