Preprocessor Error

Hi, I'm trying to model the hydrodynamics and temperature of a reservoir, so I have turned off all constituents in the Constituent Computation card, and set all constituent to 0 in the grid dimension card. However, when I tried to run the preprocessor, it stopped at "constituent control cards", with a error meassage of "forrtl:severe(47): write to READONLY file,unit 5,file CONIN$", and in the pre.err file, it says: Either illegal value or incorrect card somewhere in the following card LDOM_P OFF RDOM_P OFF LPOM_P OFF RPOM_P OFF LDOM_N OFF Does anyone know what the problem is? Any help is appreciated! Thanks, Qiang