Invalid Dimension when I use Set Analysis to a dimension to Table

[griffin2571]

I used this script when I added the dimension =Only({<[Condition of Car]={'Faulty'}>} [Status]) and the expression editor keeps showing it is okay. However, once I click okay I get an invalid dimension. When I used the alternative solution =Aggr(Only({<[Condition of Car]={'Faulty'}>} Status), Status) then I get duplicates in my data that I don't want. 

Is there a reason the first script will keep throwing back an invalid dimension? 

Status	Corporate Dealer	Location	Condition of Car
Repair Shop	Diamler	Qatar	Faulty
Repair Shop	BMW	Qatar	Good
Repair Shop	Diamler	Qatar	Faulty
Repair Shop	Diamler	Qatar	Faulty
Repair Shop	Diamler	Qatar	Faulty
Repair Shop	Diamler	Qatar	Good
Repair Shop	Diamler	Qatar	OBCD
Repair Shop	Diamler	Qatar	OBCD
Repair Shop	Diamler	Qatar	Faulty
Repair Shop	Diamler	Qatar	Faulty
Repair Shop	Diamler	Qatar	Faulty
Repair Shop	Diamler	Qatar	Faulty
Repair Shop	Diamler	Qatar	OBCD
Repair Shop	Diamler	Qatar	Faulty
Repair Shop	Diamler	Qatar	Faulty
Repair Shop	Diamler	Qatar	Faulty
Repair Shop	Diamler	Qatar	OBCD
Repair Shop	Diamler	Qatar	OBCD
Repair Shop	Diamler	Qatar	OBCD
Repair Shop	Diamler	Qatar	Orange
Repair Shop	Diamler	Qatar	Faulty

[hic]

The expression
=Only({<[Condition of Car]={'Faulty'}>} [Status])
is a valid measure, but not a valid dimension.

Unfortunaltely, the expression editor thinks the syntax is OK, when it in fact isn't.

The expression
=Aggr(Only({<[Condition of Car]={'Faulty'}>} Status), Status)
is a a valid dimension.

Where do you get duplicates?