[INFO] Input is valid [ERROR] custom.txt:1:0(0) Error parsing custom constraints

[ShadowScripts1]

i have

[ShadowScripts1]

name,class_size,instructor,segment,is_minor,B.Tech.1,B.Tech.2,B.Tech.3,B.Tech.4,M.Tech.,classroom,slot
CS101,80,A,14,No,Core,Elective,No,No,No,,
CS102,20,B,16,No,No,No,Elective,No,Core,CL1,B

in my input.csv and...

COURSE {CS101,CS102} SEGMENT {12,16,14} IN CLASSROOM {CL1, CL2} WEIGHT 5

in my custom.csv and anytime i run : timetabler -f fields.yml -i input.csv -c custom.txt -o output.csv

i get

[INFO] Input is valid
[ERROR] custom.txt:1:0(0) Error parsing custom constraints

can someone help?