You can try to use another debugger such as OllyDbg/WinDBG/etc. just to see it works fine.

Or you can do the trick with 'int3' in SoftICE: in the beggining of your myfunc function use assembler directive '__asm int3' and enable SoftICE break on int3 by 'i3here ON'

Probably it could somehow help to break SI on your function start...