flexi auth - A user authentication library for CodeIgniter

[eluser]ReyPM[/eluser]
I've been working on a site and using FlexiAuth in my development server (local virtual Machine with CentOS) I get no errors, now I move to my hosting and get this:

A PHP Error was encountered

Severity: Notice

Message: Trying to get property of non-object

Filename: models/flexi_auth_model.php

Line Number: 1770
A PHP Error was encountered

Severity: Notice

Message: Trying to get property of non-object

Filename: models/flexi_auth_model.php

Line Number: 1773
A PHP Error was encountered

Severity: Notice

Message: Trying to get property of non-object

Filename: models/flexi_auth_model.php

Line Number: 1773
A PHP Error was encountered

Severity: Warning

Message: Cannot modify header information - headers already sent by (output started at /home/reynierp/public_html/newplat/system/core/Exceptions.php:185)

Filename: libraries/Session.php

Line Number: 675

Why?