Comment 5 for bug 415719

I believe the issue at hand is that /sys/class/net/*/wireless/ interface is deprecated, and is therefore disabled in some kernels:

config WIRELESS_EXT_SYSFS
    bool "Wireless extensions sysfs files"
    default y
    depends on WIRELESS_EXT && SYSFS
    help
      This option enables the deprecated wireless statistics
      files in /sys/class/net/*/wireless/. The same information
      is available via the ioctls as well.

      Say Y if you have programs using it, like old versions of
      hal.

By the way, /proc/net/wireless is not a good alternative, since:
   In recent kernels, interfaces that are not active will not appear in /proc/net/wireless.
according to http://slackblogs.blogspot.com/2010/01/new-kernel-and-toolchains.html

So the best solution right now is probably to enable WIRELESS_EXT_SYSFS in the kernel, or to use the relevant ioctls calls in wicd.