Python if and elif not working, giving error

I'm new in Python and doing an online tutorial. I have an assignment that I can not accomplish. My problem is that when I run this code, the minimum variable stays the same to None and does not record the new value input.

maximum = None
minimum = None
while True:
    try:
        num2 = raw_input('Type here ')
        if num2 == 'done':break
        else:
            num = int(num2)
            if num <= minimum:
                minimum = num
                print minimum
            elif num >= maximum:
                maximum = num
                print maximum


    except:
        print 'Invalid Entry'


print 'Maximum is %d' % maximum
print 'Minimum is %d' % minimum