Android Studio and SQL Server

I want to connect an application with sql server, but I get the following error. Does anyone know what it can be?

07-08 01:27:29.427 3890-3890/? E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.itasur.julio.sqlserver, PID: 3890
    java.lang.VerifyError: net/sourceforge/jtds/jdbc/TdsCore
        at net.sourceforge.jtds.jdbc.JtdsConnection.<init>(JtdsConnection.java:359)
        at net.sourceforge.jtds.jdbc.Driver.connect(Driver.java:184)
        at java.sql.DriverManager.getConnection(DriverManager.java:179)
        at java.sql.DriverManager.getConnection(DriverManager.java:144)
        at com.itasur.julio.sqlserver.Principal.onCreate(Principal.java:52)
        at android.app.Activity.performCreate(Activity.java:5231)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1104)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2157)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2243)
        at android.app.ActivityThread.access$800(ActivityThread.java:135)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:136)
        at android.app.ActivityThread.main(ActivityThread.java:5019)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:515)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
        at dalvik.system.NativeStart.main(Native Method)
07-08 01:32:29.517 3890-3890/? I/Process: Sending signal. PID: 3890 SIG: 9

My code is as follows

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_principal);

        ConnectivityManager cm = (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);

        NetworkInfo netInfo = cm.getActiveNetworkInfo();

        if (netInfo != null && netInfo.isConnectedOrConnecting()) {

            Toast.makeText(getApplicationContext(), "Conectado a Internet", Toast.LENGTH_SHORT).show();

        } else {

            Toast.makeText(getApplicationContext(), "No Conectado", Toast.LENGTH_SHORT).show();

        }

        Connection connection = null;
        String ConnectionURL, servidor, db, usuario, password;

        servidor = "192.168.0.10";
        db="db";
        usuario="sa";
        password="314159265";
        try {
            StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
            StrictMode.setThreadPolicy(policy);

            Class.forName("net.sourceforge.jtds.jdbc.Driver");
            ConnectionURL = "jdbc:jtds:sqlserver://"+servidor+";databaseName="+db+";user="+usuario+";password="+password+";";
            connection = DriverManager.getConnection(ConnectionURL);
        } catch (SQLException se) {
            Log.e("bug", se.getMessage());
        } catch (ClassNotFoundException e) {
            Log.e("bug", e.getMessage());
        } catch (Exception e) {
            Log.e("bug", e.getMessage());
        }
    }