ASP.NET - C# - Format string to numeric value

I have a value I am retrieving from a database.  I am assigning the value to a text box on my asp.net form.  The field in the database is a money value.  I want the below result.

Database Value     Result Value
0.000000                0.00

I have tried the following

string s = string.Format("{0:c}", rdr["myValue"].ToString());
this.myTextBox.text = s;

and

string s = string.Format("{0:#,0.00}", rdr["myValue"].ToString());
this.myTextBox.text = s;

But neither works.

Any ideas?