Hi @MajidAbbasi -
I have an educated guess about what’s going on here (I downloaded your workflow to check, but the data wasn’t included). The Strings to Document node will include whatever you choose for the title as part of your corpus. So, if you have a long title and relatively short text - and it looks from your workflow like you are processing single sentences - noise from the title may be dominating your model and causing strange results.
Unless your title contains key info you want included as part of your analysis, it might be better to set the title to an empty string, or at least a very short unique ID.