My function returns what the question is asking for, why is it not being accepted?

#combiner function takes a list and combines string type and sums integer and float types, returns as one string.
def combiner(lst):
    #empty lists and string that for loops will use.
    str_list = []
    new_combined_str = ""
    num_list = []
    #this loop iterates through lst and pulls out element type string and puts them into str_list.
    for i in lst:
        if isinstance(i, str):
            str_list.append(i)
    #this loop interates through the str_list and concatenates them into one string.      
    for i in str_list:
        new_combined_str += i
    #this loop iterates through the list and pulls out elements type float and puts them into num_list.
    for i in lst:
        if isinstance(i, float):
            num_list.append(i)
    #This loop iterates through the list and pulls out elements type int and puts them into num_list.      
    for i in lst:
        if isinstance(i, int):
            num_list.append(i)
    #sum all elements in num_list      
    num_list = sum(num_list)
    #change num_list to type str and concatenate with new_combined_str
    new_combined_str = new_combined_str+str(num_list)

    return new_combined_str