"Encountered an improper argument" error when deleting conditional tag

[dsarig]

I am using RoboHelp 2015. I am trying to delete a specific conditional tag from the Conditional Tab pane and am getting the following message: "Encountered an improper argument". I can delete other tags, but not this specific one.

[dsarig · Accepted solution]

I removed unused expressions from the Conditional Build Expressions field and now the problem is not happening.