If statements are skipped C

Again a quite simple question. I've been struggling all night.
Why does it not jump into the if-condition if month = 11? It just skips this the if statements. I think normally the debugger would check each if statement but here the compiler isn't doing anything. It's just skipped.

int get_weekday(int day, int month, int year)
{
    int nday, nmonth, nyear, jahrhinten, ncentury, nleapyear, res, weekday;

    nday = day % 7;
    printf("%i\n", month);

    if ((month == 1) || (month == 10))
    {
        nmonth == 0;
    }
    else if(month == 5)
    {
        nmonth == 1;
    }
    else if(month == 8)
    {
        nmonth == 2;
    }
    else if ((month == 2) || (month == 3) || (month == 11))
    {
        nmonth == 3;
    }
    else if(month == 6)
    {
        nmonth == 4;
    }
    else if ((month == 9) || (month == 12))
    {
        nmonth == 5;
    }
    else if ((month == 4) || (month == 7))
    {
        nmonth == 6;
    }

    jahrhinten = year - 2000;
    nyear = (jahrhinten +(jahrhinten / 4)) % 7;

    ncentury = (3-(20 % 4))*2;

    if(((year % 4)== 0) && (month == 1 || month == 2))
    {
        nleapyear = 6;
    }
    else
    {
        nleapyear = 0;
    }

    res = nday + nmonth + nyear + ncentury + nleapyear;
    weekday = res % 7;
    return res;
}

Thank you really much in advance.