I created two text layers. I typed one line on the one. I had the other one tell me what character letter where I indexed. For example, I typed, "Index me." When I indexed the third one, the second text layer should say, "d" in "Index me." The expression "thisComp.layer("Index me").text.sourceText.value" does work, but when I added a slider expression (named "Indexing Character Value"), the expression was disabled and said, "Error at line 3 in property 'Source Text' of layer 2 ('Index'). property or method name '[object Property]' in Class 'String' is missing or does not exist. It may have been renamed, moved, deleted, or the name may have been mistyped."