Look at your connection string:
String ConnStr = ("Data Source=192.168.200.246;Initial Catalog=BackOffice_Report;Persist Security Info=True;User ID=sa,password=");
is a "special user" who normally has absolute power over the database, and id constructed for you when you install SQL server. This installation has a password, which is often changed, and the account removed entirely. But it would only be a very stupid or naive database admin who would clear the password field entirely, as this would allow everybody access to all the tables of all the databases in the SQL server instance - dangerous and definitely not a good idea.
You either need to use the correct password, or (more likely) use the proper username and password combination with access only to the databases / tables you really need.