A problem with reading ephemeris files

[MarinChernyak]

Hello!
I am experiencing the problem with calculations of asteroids. I am using VS2012/WinForms/C#
This is my try to compute position of Chiron. First, I checked whether the file is existing.
bool f1 = File.Exists(@"C:\SWEPH\ephe\seas_18.se1");
f1 is true, so - it is existing.

Next:

sweph.swe_set_ephe_path(@"C:\SWEPH\ephe");
iflgret = sweph.swe_calc_ut(JD, SE_CHIRON, Constants.SEFLG_SPEED, dCoordinates,ref serr);

iflgret get -1.
the error message: SwissEph file 'seas_18.se1' not found in PATH 'C:\SWEPH\ephe'

I have downloaded the file seas_18.se1 from GitHub... It was working fine in a project, which written in C++.
What is wrong?
Thanks for advance for your response!

[ogaty]

maybe you should write OnLoad Event.
like this
https://github.com/ygrenier/SwissEphNet/blob/1930ecd5fdc0b0f00c45a2b0dae80671b095c7ac/Programs/SweTest/Program.cs#L2239-L2251