keep getting a syntax error by line 23

SIR_CHARGE = 2

TICKET_PRICE = 10

tickets_remaining = 100

def calculate_price(num_tickets):
    return ( TICKET_PRICE  * num_tickets) + SIR_CHARGE

while num_tickets  >= 1:
    print("There are {} tickets remaining.".format(tickets_remaining))

# Gather the user's name and assign it to a new variable
name = input("What is your name?  ")

# Prompt the user by name and ask how many tickets they would like
num_tickets = input("How many tickets would you like, {}?  ".format(name))
try:
    num_tickets = int(num_tickets)
# Calculate the price (number of tickets multiplied by the price) and assign it to a variable
    if num_tickets > tickets_remaining: 
        raise ValueError("there are only {}  ".format(tickets_remaining))
    except ValueError as err:
         print(" ok no prop man {}".format("err"))

    amount_due = num_tickets * TICKET_PRICE
# Output the price to the screen
print("The total due is ${}".format(amount_due))