#ERROR Coming with date

Hi Experts,

I am using the below logic to get the previous year starting date:

=ToDate("4/01/"+FormatNumber(Year(ToDate([L01 Billing doc. date]Where(Year([L01 Billing doc. date])=Year(CurrentDate())-1);"M/dd/yyyy"));"####");"M/dd/yyyy")

This Logic is working fine but giving the #ERROR with date like below picture:

How to resolve this.

Thanks,

G Sampath Kumar