Well, explanation is simple : the BTC TAb should not exists on Bitstamp.

First of all it's important to understand the Concept of Market & Partner Currency.

The Market Currency is the Currency you buy/sell. In other words is the currency that you express in QTY
The Partner Currency is the Currency you use to make che Price.

Ex : Buy 1 BTC (Market) @ 700 USD (Partner)

GAINS are always expressed as PARTNER Currency.
When C.A.T. load all the markets is able to understand in automatic mode all the PARTNER Currency and then Create the GAIN TABS (1 Partner Currency = 1 Gain Tabs).

On Bitstamp, your Markets are

btc (Market) - usd (Partner)
eur (Market) - usd (Partner)
btc (Market) - eur (Partner)

So, you will never have a GAIN Expressed as BTC value, but only with USD or EUR Value, because BTC is never a Partner Currency.

Ex :

If i sell 1 BTC @ 800 USD then i bought 1 BTC @ 790 USD, My Gain is 10 USD.


Probably is the same for the YOBIT CAse.....