The following is from on-line help on the Range property, and explains
why it doesn't need a qualifying object. (Typically the qualifying
object would be a reference to the worksheet that the range is on):
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"When used without an object qualifier, this property is a shortcut
for ActiveSheet.Range (it returns a range from the active sheet; if
the active sheet isn't a worksheet, the property fails)."
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The Cells property is less forgiving. Thus you would need to qualify
it as (for example) :
'Only if abc is the current sheet!
'Otherwise, add the line
'Worksheets("abc").Select
'first.
Worksheets("abc").Cells(1, 1).Select