Invalid Syntax error on relatively simple if statement

I'm pretty new to Python and am taking a CS 170 course in it for my degree. I'm encountering an error in my code that I can't seem to resolve and my professor has been all but helpful. Any tips would be greatly appreciated!

When I run my program, I get an invalid syntax error that highlights the colon of my if statement, I'm attaching the code around the error so that ya'll can see it and maybe be able to help. Let me know if you need anything more. Thanks in advance!

float(year)
y = int(float(year))
float(month)
m = int(float(month))
float(day)
d = int(float(day)

if get_valid_date(y, m, d):

        day_number = zeller(year, month, day):
        print_date(day_number)

else:

    print('The date is invalid')