Formula field - Error: Number and Text cannot participate in an expression together

Hey everyone,

I get the error "Error: Number and Text cannot participate in an expression together" whenever I try to use an IF statement in a formula field. For example, the below formula doesn't work

DATEADD(NOW(),IF(DAY(NOW())<CASE([Day],“Sunday”,0,“Saturday”,6,“Monday”,1,“Tuesday”,2,“Wednesday”,3,“Thursday”,4,“Friday”,5),CASE([Day],“Sunday”,0,“Saturday”,6,“Monday”,1,“Tuesday”,2,“Wednesday”,3,“Thursday”,4,“Friday”,5)-DAY(NOW()),7+CASE([Day],“Sunday”,0,“Saturday”,6,“Monday”,1,“Tuesday”,2,“Wednesday”,3,“Thursday”,4,“Friday”,5)-WEEKDAY(TODAY())),“days”)

Any suggestions?