Current Week Course and Assignment

Hello,

I tried to populate the Assignment cell D12 of Current Week View sheet but this formula isn't working. Does anyone know why not? My objective is to populate the cells C12:L21.

Thank you for any help or suggestions,
Billy

Formula:

=IFERROR(INDEX(Assignments!$C:$C,SMALL(IF(Assignments[Due Date]=DATE(WkYear,WkMonthNum,C$10),ROW(Assignments[Assignment])),ROWS($1:1))),"")