In that case then these are the two most likely causes of your issue:

1. You've misspelled the variable name. Might sound silly but it's worth checking and then checking again!

2. Your variable is out of scope. For example, if your script component isn't in any other container in the control flow, e.g. sequence container etc then the scope of the variable you're calling needs to be at the package level. You can check this in the variables tab.

Rob.