[cctalk] TRS-80 BASIC oddity

I am going to assume there are other TRS-80 people hanging out here and go ahead and ask this: Has anyone here used the DEFUSRx command? I tried to use it for something I am working on and it didn't work. So, I copied the example program from page 115 of the Model III Disk System Owner's Manual and, guess what, it didn't work either. 150 DEFUSR1 = &H7D00 returns a Syntax Error 150 DEFUSR1 = 32000 works fine. Anybody else ever run into this? I can't believe something as blatant as that could have gone on for all those years. bill