viscous dampener with combin14

[robfer85]

Hello, everyone! I've been banging my head for a couple of days on this issue and I just can't figure out where I'm wrong, I hope someone can help me.
I am building an ansys12 model on which to carry out a transient analysis, in which I have to apply an accelerogram to some knots that are bound by viscous dampeners, simulated with the combin14 element. I then apply a variable force in time equal to:
f(t)= cv*v(t)
in which v(t) is the time history of the speed of my accelerogram. I can perform the analysis, but the shift that I get into the node in question is exactly half the exact one calculated by integrating the v(t).
So I did a test on a single combin14 element between 2 knots, and I get the same a halved shift. this is the code I used:

/prep7

#1,0,0
No,2,1,0

et,1,combin14

r,1,1

type,1
real,1
e,1,2

nsel,all
d,all,uy,0
d,all,uz,0

♪
d,all,ux,0

/solu
antype,trans
Trnopt.

*dim,time_hist,table,2001,1,1,time,x
*tread,time_hist,wave,txt

outres,nsol,all
_
_
tm_incr=0.005

*do,tm,tm_start,tm_end,tm_incr
time,tm
♪
f,all,fx,%time_hist%
nsel,all
The
*end
finish

Does anyone have an idea where the mistake might be?