If you are using SoD or Underfoot with a recent PEQ database, then the database is setup to send those clients to the new (V3) version of nektulos which requires the nektulos.eqg file.
You should have nektulos.eqg (around 14,895,061 bytes in size) unless you renamed or deleted it. nektulosa.eqg is something completely different.
If you find your missing nektulos.eqg, you might still have trouble zoning into nektulos if you have the current version of SoD from Steam (which we call Underfoot), in which case you will need to source in the SQL from this post:
http://www.peqtgc.com/phpBB2/viewtopic.php?t=11639