Loading and using a codeigniter model from another model

Fellow coders, using codeigniter 1.7.3 can I load a model from the code of another model? I have read many posts theoretical and practical but none gave a final answer.

I have a model that has a function in which i would like to perform an operation on another model. the code is like this:

1: $this->load->model('decision_model');
2: $this->decision_model->hello_decision();  

line 1 works. line 2 fails as follows:

A PHP Error was encountered
Severity: Notice
Message: Undefined property: Account_model::$decision_model
Filename: models/account_model.php

I have tried creating simple dumb models, changed function names, giving the model an alias when loading it, etc... no luck

So, theory aside, is this doable?

thanks in advance.