All is fine with this report writer
To solve your problem you must have to specify a format and to do this:
Double click on field (or control) and in format you can set a mask like this: 9,999,999,999.99 or 999999999.99 or like you want
any other formats go together: @Z 9,999,999,999.99 ans so on.
Be fast like the Fox
Be free like the Penguin
Se Rápido como el Zorro
Se libre como el Pingüino