Dear Colleagues, 
Greetings, 

Please HELP! I am working on "Sorption" module simulations for MMT removal of heavy metals. However, for more than three weeks now I am trying to fix the group charge issue I am facing. I have tried uff, clayff and modified uff. I keep getting this message when I calculate the charges from "Modify" tool: 

"No charge groups have been calculated.
The particles that are being considered for a charge group are not charge neutral.
The absolute net charge is 15.9955 and it should be less than 0." 

What could be the issue? 
The file is attached herewith. 
Regards, 
Hamzah