The specified vertical relative moving angles are not in the correct order. The vertical factor file or table is an ASCII file with two columns. The first column identifies the vertical relative moving angle (VRMA) in degrees, and the second, the vertical factor (VF). Each line in the file specifies a point in a vertical-factor graph. Two consecutive points produce a line segment in the VRMA-VF coordinate system. If the VRMAs are not in ascending order, the line segments can cross, resulting in ambiguous VFs.
Make sure the vertical relative moving angles are sorted in increasing order.