To determine why you cannot perform a fit model in JMP, you would need to provide more information about the specific error or issue you are encountering. However, based on the given data, there are a few potential reasons why the fit model may not be working properly:

1. Insufficient data: The dataset provided is relatively small, with only 15 observations. In some cases, this may not be enough data to accurately fit a model or detect significant relationships between variables.

2. Lack of variability: If the variables in the dataset do not exhibit enough variability or range, it may be difficult to identify meaningful patterns or relationships. This can make it challenging to fit a model accurately.

3. Non-linear relationships: If the relationships between the variables are non-linear, a linear model may not be appropriate. In such cases, alternative modeling techniques, such as non-linear regression or polynomial regression, may be more suitable.

4. Outliers or influential observations: The presence of outliers or influential observations can significantly impact the fit of a model. If there are extreme values in the dataset, they may be distorting the results and making it difficult to obtain a good fit.

Without more specific information about the issue you are facing, it is challenging to provide a more precise explanation. It is recommended to review the error message or consult the documentation or support resources for JMP to troubleshoot the problem further.