simple IFS formula. what am i doing wrong here?

SEANSKIM15 

In lieu of IFS, try:

=LOOKUP(B1, {0, 60, 70, 80, 90}, {"F", "D", "C", "B", "A"} )

SEANSKIM15 Your formula look correct. What is your excel version? Do you have access to IFS() function on your version of excel? Below formula give me correct result.

=IFS(B1>=90,"A",B1>=80,"B",B1>=70,"C",B1>=60,"D",B1<60,"F")

Based on regional and language settings, you may need to use semicolon (;) rather than comma (,). You B column data may stored as text. Otherwise your formula structure is correct.