Syntax problem in C#

Question

var temp = ConfigurationManager.ConnectionStrings["connectionStr"].ConnectionString;

conn = new SqlConnection(temp);

conn.Open();

// Create the command

SqlCommand command = new SqlCommand("SELECT * FROM View_Patients", conn);

command.Connection = conn;

RecCount = Convert.ToInt32(command.ExecuteScalar());

 

last line giving the error "Input String was not in a correct format"