C# is Case Sensitive and if the IntelliSense is not showing try out it through Tools->Options to turn it on for all language. The listbox have the property called "SelectedValue" not "Selectedvalue".
The another exception you posted here over the formation of SQL string by calling a function, you missed out the parentheses [FormatSQLString()] so the exception might be that "FormatSQLString" is a function but used like a property.
VB will automatically add the parentheses with the functions but C# don't. So you need to be little careful when you are doing it in C#. Happy Coding...