Call Methods are used when a script contains a function that playmaker can read.
In most cases it can't. So you have two options:
1) Drag the script from the inspector tab into the empty area inside a state where you place your actions. You can then Get or Set it's property. In this case select Get. Then you'll have options that may allow you to get that variable.
2) If the above doesn't work, copy that script and paste it into GPT asking it to allow you to be able to read it in playmaker. It may make a mistake or two. Trial and error, until you get it right. This usually takes a minute at best.
Hope that helps you.