Navid2000, Going by your syntax, I believe you are using the Unload utility. This Utility is very restrictive on what it can do. It unloads by accessing a Table space. If you only have one table per table space, you can only unload the one table. If you have 2 or more tables in the same table space, you can unload from those tables with one Unload Utility statement.
Also, you can not join tables (or use subqueries, I believe). If your view does any of these things, it can't be used. And because of its restrictive nature, I would be surprised if it can unload from a View at all (there is no mention of this ability).
You should have the IBM DSNTIAUL program available. If you use this with the PARMS(SQL) option, it indicates it will accept any valid dynamic SQL Statement. Since using a View is valid in dynamic SQL, you should be able to use DSNTIAUL program to Unload using a View. But I don't think you can unload to a CSV file as you are trying to do.
There is a third option but you have to pay for it. There is an IBM High Performance Unload (HPU). When you supply HPU with an SQL statement that it can't not process directly, it call DSNTIAUL to perform the SQL. You can define CSV output and I believe it will the output will be in CSV format even if the SQL was passed to DSNTAIUL.