I am fairly competent with Sound Forge Pro 9 but just now have found that when I select and highlight a tiny part of a file containing a transient click or pop, and then reduce its level by say 20 db., it does not respond to it. - The amplitude stays the same.

I have been doing this sort of treatment for years with no trouble but cannot figure why just this is not working now. There is no obvious problem with the program, - everything plays and selects and I can EQ. OK as well. - Anyone else had this problem ?

RonC.

Try changing the 'Cross-fade' attribute to a linear 'X' parameter (see below graphic) under the 'More' tab in the 'Volume' or other process/plug-in selection window. The default cross-fade parameter does not work for very short duration selections.
Another option to remove clicks/pops and such is via the "Replace" process under "Tools> Repair" menu with the offending click/pop selected.