groovy.lang.MissingMethodException: No signature of method: java.lang.String.pos

Hi     I am getting error in the groovy script if i am declaring string message as follows: String msg = "MSH|^~\\&|HIS|RIH|EKG|EKG|199904140038||ADT^A01||P|2.2\r"                 + "PID|000...