Trying to create a list that by change the start date in a cell will create all workdays for that month excluding weekends and preset holidays

I am working on for my job an excel productivity tracker i am trying to create a formula that will list all work days excluding holidays that i put in a cell range from the start date that i will from cell a1 by entering in m/dd/year but using workday(a1,sequence(30),b1:b5) errors out when i use it for September-December just shows #### for random week days throught the months and i dont know why can someone offer some advise