Regarding your other question, if the strategy fails with other scrips, should i dump it?
Different stocks have a different movement. Because they are affected by different fundamentals and different type of traders. A stocks movement and patterns are created by the traders who trade them and there are different types of traders present in different markets (Eg. scalpers, Mean reversion traders, Trend traders, swing traders etc.). For various reasons different group of traders choose to trade different instruments. It is the inherent behavior of these groups that is responsible for characteristic pattern in movement of a particular instrument. Hence pattern in movement of different instruments differ and not all strategies perform similarly on different instruments.
Well ideally a good strategy is the one that is also robust. This means that returns, drawdown etc. should not change a lot. Some variation is obviously expected but it should not give completely opposite results.
When you are trading in markets, you are competing with the market and the market consists of people who participate in it and among those people are some of the best brains hence you need to act really smart to make consistent profits.