How to apply indicator on custom series?

I have created a custom series using various instruments (a simple example could be (scrip1 + scrip 2 )/Scrip 3).
I want to apply technical indicators onto this custom series. I am able to use MA and Bollinger, but unable to use RSI and Stochastic which invariable picks the scrips displayed in the chart.

Please advise how to use technical indicators on custom series.

Thank You

@snehalsoni the RSI indicator in AmiBroker uses the Close price.

If you search and study the documentation, a good thing always to do before posting questions in the forum, for the RSI - Relative Strenght Index you'll see that there is also a variation called RSIa

RSIa( array, periods = 14 )

This second version RSIa accepts as in input an array so you can directly apply the RSI formula to your custom series.

In addition to that, in the Comments section you'll also find a sample formula that explains how this oscillator is implemented internally (just in case you want to create your own variation!...).

The Stochastic Oscillator is another momentum oscillator that it is internally implemented on the default price series. When there is no alternative, you can always do a Google search to find the formula used to calculate it and implement it in AFL (in the Member's Zone library there are some variations).

Taking the time to study the documentation is always is time well spent!