A trending market can move between parallel support and resistance levels. A price channel between two parallel lines can often be drawn in a trending market. The key to a price channel is that the lines be parallel to each other. The value of the price channel in predicting the ongoing speed of a trend depends on the lines being parallel.
Unlike trend lines, which can be drawn on any chart with two relative lows or highs, price channels should not be forced on a chart where they are not quickly apparent. Once a trend line is established, create a duplicate parallel line on the chart. Then move it up to the relative highs above or down to the relative lows below the trend line. If two or more fit with the line, there may be a valid price channel. Otherwise, the market may simply be too volatile – even in the midst of a strong trend – to plot a channel.
In the above example the (support) trend line itself is valid, but creating a parallel line on the opposite side of the prices does not add any value to the chart and is not warranted by the data. Placing a support or resistance line where it does not belong will simply provide you with false signals to buy or sell.