Bitcoin increases do not always have a negative impact on alt coin. Sometimes alt coin increases as btc increases.
That's because there are 2 forces at play here. One is the thought that BTC is paving the way for the rest. When it becomes popular all cryptocurrencies appear in the media, the interest rises and so do the prices.
The other thing is that some cryptos oppose BTC and/or are feeling the niche to give their users features that BTC doesn't have, like better encryption, better anonymity, faster and cheaper transactions, cheaper and easier POS mining, and so on.