If your indicator is either tick-based or volume based, you may need to adjust the volume settings in TradeStation for it to work properly.
For example, if you're using an indicator that's counting ticks, you'll most likely need to adjust the For volume, interval setting from "Trade Vol" to "Tick Count", as shown in the following diagram.
On the other hand, if your Volume indicator doesn't appear to be working correctly, you may need to adjust that same setting to be "Trade Vol" rather than "Tick Count". Experiment with this setting to see if it resolves the issue you're having.
Note that if you have a tick-counting indicator and a volume-counting indicator on the same chart, they may not be able to both function correctly if they require the "other" setting. In this case, you may need to use only one type of indicator on the chart, and use the other indicator on another chart that uses the correct For Volume, setting.