A problem with LookupPrivilegeValue.

I've seen SE_IMPERSONATE_PRIVILEGE constant value in MSDN.
When I'm trying to use as a parameter in LookupPrivilegeValue, "undeclared identifier" error appears about the usage of this constant.
OK, then I'm trying to use it's symbolic name "SeImpersonatePrivilege". After this GetLastError returns an error, which is about uncorrect privilege name.
What must I do to use this privilege?

The code was tried on Windows 2000 SP3, so the privilege value must be supported by OS.