AIC, AICC NaN question

Hi, I want to use AIC or AICC to evaluate fitting model. But when I run the following code in which sample is an array of sample data, I got NaN for AIC and AICC. Do you know what is the possible problem? Thanks, –Li

ConditionalSumOfSquares fitting=new ConditionalSumOfSquares(sample, 1, 1, 1);
ARIMAModel arima=fitting.getModel();

System.out.println(“AIC:”+fitting.AIC());
System.out.println(“AICC:”+fitting.AICC());