"if in" & "if not in" condition not triggering

First, I apologize if this is not the right place for this. I'm getting a code error when trying to Solve this task. I believe the error is because the "if in" and "if not in" conditions aren't triggering properly. I do pass the "Run" test, but not the "Check" test. I'm not certain what I am overlooking; maybe someone can point me in the right direction as to why the "if in" and "if not in" statements never trigger?

exclude = ['.:!?@$%']

class HackerLanguage:
    def __init__(self):
        self.text = ""

    def write(self, text):
        self.text += text

    def delete(self, num):
        self.text = self.text[:-num]

    def send(self):
        res = ""
        for letter in self.text:
            if letter not in exclude:
                res += str(bin(ord(letter)))[2:]
            else:
                res += letter
        return res

    def read(self, rd):
        self.rd = rd
        res = ""
        x = 0
        while x < len(rd):
            if rd[x] in exclude:
                res += rd[x]
            else:
                res += chr(int(rd[x:x+7], 2))
                x += 7
        return res