Return Blank cell is text NOT found

[The Animal]

Hi
I have below that returns the value in S21 if "Casual" OR "Part Time" is found in "M21"
=IF(OR(ISNUMBER(SEARCH("Casual",$M21)),ISNUMBER(SEARCH("Part Time",$M21))),S21)

If either of those words are NOT found then returns a FALSE.
I need to return a "" blank cell if anything other than Casual or Part Time is found in M21?
Any help would be great
Stephen

 

[shg]

...,s21,"")

 

[The Animal]

That easy Hey
Thanks so much.