[gentoo-user] asterisk zaptel-1.2.9.1 error

[Kitti Jaisong]

Title: asterisk zaptel-1.2.9.1 error

Hi all,
    I'm emerge zaptel 1.2.9.1 and get error like this

 checking zaptel-1.2.9.1.tar.gz ;-) ...                                 [ ok ]
 * Determining the location of the kernel source code
 * Found kernel source directory:
 *     /usr/src/linux
 * Could not find a usable .config in the kernel source directory.
 * Please ensure that /usr/src/linux points to a configured set of Linux sources.
 * If you are using KBUILD_OUTPUT, please set the environment var so that
 * it points to the necessary object directory so that it might find .config.

!!! ERROR: net-misc/zaptel-1.2.9.1 failed.
Call stack:
  ebuild.sh, line 1562:   Called dyn_setup
  ebuild.sh, line 665:   Called pkg_setup
  zaptel-1.2.9.1.ebuild, line 81:   Called linux-mod_pkg_setup
  linux-mod.eclass, line 432:   Called linux-info_pkg_setup
  linux-info.eclass, line 554:   Called die

please help me

ti