Hello Ludovic,
The number of arguments has changed for VEL_PROF_Z subroutine since release v7p0.
If using VELOCITY VERTICAL PROFILES = 0 (user defined), start from the subroutine USER_VEL_PROF_Z of the release you use (v8p2r0 is recommended now, but it is the same for v8p1r1) and write your modifications inside. The user subroutine USER_VEL_PROF_Z is called by VEL_PROF_Z with this option 0 for the keyword.
Hope this helps,
Chi-Tuan