Whoops........
Okay I when back and re-tried it.
It's the same issue just different method.
call2.setNull(0); << Syntax error
call2.setNull(1); << same
call2.setString(2, "dbName");
// came problem
call2.setNull(0, Types.VARCHAR); <<Invalid parameter binding
call2.setNull(1, Types.VARCHAR);
call2.setString(2, "dbName");
I checked on the types too.
Based on this link :
SQL Server TO JDBC Types
NVARCHAR = VARCHAR
SYSNAME = VARCHAR