Hi riesta,
What I meant was that if it is not working for the other types of documents is because your FileType value is not a correct mime type.
Since you are filling the parameter from the database, you can check what you have in the database for the table Assignment. In order to do that, you right click the table Assignment on the tab and select option View Data:

When you do that, you will see the records you have in your table Attachment (in my screenshot empty but on your with results) and you can see if the FileType is correct according to the examples I showed you:

If your file is of type PDF, then your FileType field in the database should be application/pdf in order to work, and for the Excel and Word like I mentioned above.
Cheers,
João