"model is lacking" is a grammatically correct and usable phrase in written English.
You can use it when you are trying to describe something as not having the full required components or not being complete. For example: "This model of mobile phone is lacking features essential for a modern user."
In literature, the experimental validation of a glass edge strength model is lacking.
This paper presents a new approach for performing feasibility analysis over a multivariate factor space when the explicit form of a process model is lacking or when its evaluation is expensive.
Although there are several animal models of NASH, consensus regarding the optimal model is lacking.
Despite these interdependencies in in-store logistics and space assignment, an integrated optimization model is lacking in the existing literature.
For Germany we recently reported first results of an administrative data Approach [2] but a risk model is lacking.
Child neglect is the most common form of child maltreatment, yet the biological basis of maternal neglect is poorly understood and a rodent model is lacking.
Monitoring drift ice in the Arctic and Antarctic regions directly and by remote sensing is important for the study of climate, but a unified modeling framework is lacking.
The heretofore boring Sienna gets a much-needed personality transplant with an infusion of the Venza's good looks along with a dose of the utility that model was lacking.
While such a model is biologically plausible, experimental data to justify such a model are lacking.
While several realizations of the Guyton model are or have been disseminated as computer programs, human readable expositions of the various versions of the model are lacking.
External validation of C-SSI risk prediction models is lacking.
