Expert advisor

Expert Advisor: enable traders to automate their trades with a customized EA that best fits their needs.

Script

Is a program intended for a single execution of some actions. Unlike Expert Advisors, Scripts are not run tick wise, but on request.

Custom Indicator is a technical indicator written independently in addition to those already integrated into the client terminal. Like built-in indicators, they cannot trade automatically and are intended for implementing of analytical functions only.

Indicators
Actually Indicators are indicating the trend, Indicators are tools for analyzing the market trend, not any particular level, they can help you to forecast some technical levels but not an exact level. How can any indicator predict any exact level. Sometime some indicators work and few indicators don't work, it cannot be possible that every time in any situation each and every indicator work.