Hey,

You are doing it wrong. If you want to check the file format you need not use “File extension” option under If Statement..

You can just use the String Condition in If statement

In your source value you will write $currentFile{extension}$, your operator will be ‘Equal to’ or ‘Not equal to’ (based on your requirement) and your Target value will be pdf. 

Hope it helps.

@lathab You can use it like this, it is expecting a list variable not string: