add logo to slides when using beamer

[Jeremy C. Reed]

I have been using beamer off and on for a few years. I am currently using 
lyx 1.5.4 and my beamer is from pkgsrc package teTeX-texmf-3.0nb5.

I am trying to get a logo printed on every slide (PDF page). I have this 
in a ERT:

\pgfdeclareimage[height=2cm]{ISC-gears2}{ISC-gears2.png}

\logo{\pgfuseimage{ISC-gears2}}

But I don't see any logo. I am reading through the beameruserguide.pdf. 
Any suggestions/hints/examples would be appreciated.

  Jeremy C. Reed