I just looked at the Process Examples - Collections and the syntax that gives seems to suggest your input should be ""[Salary]>1000"". I guess because you are passing through the collection which could be renamed by the Filter Collection action itself the name of your collection is not used by the VBO code.
Another option would be to use the OLEDB VBO to query your excel worksheet - it is fairly easy, effectively your spreadsheet can be queried as though it was a database. There is lots of help on the internet about using OLEDB against Excel.
BTW - if the fact you did not look at the Process Examples means you do not know about our Process Templates which are available in the same page on the portal, I recommend you look at them as a matter of urgency. Using process templates should be mandatory for all your solutions.