I got the error message forrtl: severe (38): error during write, unit 5, file CONIN$

Hi, When I run the preporcessor, the pre.err gives me that error: Either illegal value or incorrect card somewhere in the following card POM_N OFF CST DERI CDWBC CDWBC CDWBC CDWBC CDWBC CDWBC DOC OFF POC OFF And the error message is forrtl: severe (38): error during write, unit 5, file CONIN$ My model consists of 1 waterbody whit 1 branches, 3 segments and 40 layers. I run the preprocessor a lot of time and it keeps failing at constituent control cards. I am not sure if it is the error in my W2 con.npt file or the error in fortran file pre.f90? Please give me help/suggestions. Thanks, Yi-Jing