Command Button - Clear

can i delete data (a1:b20) in sheet 1
and data in (a1:b20) in sheet 2
thru a command button

actually i did try to do this as below. but this is giving me a
"run time error 1004"
"select method range class failed"

any help on where i am going wrong

Private Sub CommandButton1_Click()
Sheets("sheet1").Activate
   Range("a1:b20").Select
   Selection.ClearContents
   Sheets("sheet2").Activate
   Range("a1:b20").Select
   Selection.ClearContents
end sub