Question: Invalid specification of initial conditions

I have the following diff equation with IC that I am trying to solve but I always get the "invalid specification of initial conditions" message. Here is the definition of the function and IC:

alpha:=0.024:g:=9.81

var:={x(t),z(t),dx(t),dz(t)}:

eqn:=diff(x(t),t)=dx(t),diff(dx(t),t)=-0.51*alpha*dx(t)*v(t),diff(z(t),t)=dz(t),diff(dz(t),t)=-g-0.51*alpha*dz(t)*v0(t):

initcond:=x(0)=0,z(0)=h,dx(0)=v0*cost(theta),dz(0)=v0*sin(theta):

h:=1,v0:=25,theta:=15,w:=20:eta:=1:

sol:=dsolve({eqn,initcond},var,numeric);

Any suggestions on what may be wrong and how to solve the equation?

Thank you

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