Palindrome, problem with isalpha

I don't know if I am implementing isalpha() correctly and doing something else wrong or it's in the wrong place. Where I have the isalpha now, once I compile and run it, it say everything is palindrome, which is definitely not right. What am I doing wrong?

Thanks

Here is the palindrome function, I don't think I need to post the main because it was given by my professor and there is no need to change it. If you need it, just say so.

Code:

---

int is_palindrome(const char *message)
{
       
        int k = tolower(strlen(message) - 1);
        int j;
       
        for(j = 0; j <= k; j++)
        {
                if(isalpha(tolower(message[j]) != tolower(message[k])))
                {       
                        return 0;
                }
     
        k--;
   
        }
         
        return 1;
}

---

I can think of no valid purpose for isalpha to serve here. The result of != is always either 0 or 1, and neither of those are alphabetical characters in ASCII.

In other words: "My program is not functioning correctly. I am thinking it is the result of a function that has been widely in-use for almost three decades."

Does that about sum it up? Because that isn't even a question, buddy.