Drift Diffusion and Heavy species transport coupling

Hello

I am modelling an AC-DBD plasma actuator (model is attached). I have modeled my time-dependent ac circuit and have proceeded to include the drift diffusion model and heavy species transport module to include the plasma chemistry and calculate the electron density and mean electron energy (output from drift diffusion). In my perspective, i have coupled the heavy species module and drift diffusion properly. But on running the simulation, the solver shows an error stating:

Failed to evaluate variable Jacobian.
- Variable: comp1.hs.ebar
- Geometry: 1
- Domain: 1 4
- Feature: Time-Dependent Solver 1 (sol1/t1)

I have several questions
1- How can i resolve the above problem?

2- I also want to derive an expression for body force after i include the fluid module (laminar and incompressible flow). Will it be possible? The body force calculation requires the charge density and electric field. I can output the value of electric field using comsol and i think i can do the same with the charge density (correct me if i am wrong). But the model should also plot the body force vectors (preferably) under the results section. Will this be possible with the capabilities of comsol 4.4 or higher versions?

I sincerely appreciate your help in this regards.

Thank you

Best regards
Zaid