VRWorks 360 Rig Calibration Issue

Hello,
We want to use VRWorks 360 for stitching frames from four fisheye cameras in mono mode, but can’t pass calibration routine. We used nvcalib_sample application with ours .xml rig description and frames. But calibration process fails with NVCALIB_ERROR_FAILED_CONVERGENCE.
Description of lenses we are using is here http://www.fujifilm.com/products/optical_devices/pdf/cctv/fa/fisheye/fe185c057ha-1.pdf
Xml description is the following:

<?xml version="1.0" encoding="utf-8"?>
<camera_rig coord_axes="z-up" rig_diameter_cm="35.000000">
	<camera width="1248" height="1248" layout="equatorial">
		<input_calib_file name="1.jpg"/>
		<pose>
			<rotation yaw_deg="0.000000" pitch_deg="0.000000" roll_deg="0.000000"/>
			<translation x_cm="-16.5" y_cm="0.0" z_cm="0.000000"/>
		</pose>
		<optics>
			<focal_length focal_pixels="386.204524"/>
			<principal_point center_offset_x="0" center_offset_y="0"/>
			<lens type="fisheye" k1="1" k2="0" k3="0" k4="0"/>
			<fisheye_radius radius_pixels="624"/>
		</optics>
	</camera>
	<camera width="1024" height="1024" layout="equatorial">
		<input_calib_file name="2.jpg"/>
		<pose>
			<rotation yaw_deg="90.000000" pitch_deg="0.000000" roll_deg="0.000000"/>
			<translation x_cm="6.0" y_cm="-23.5" z_cm="0.000000"/>
		</pose>
		<optics>
			<focal_length focal_pixels="316.830175"/>
			<principal_point center_offset_x="0" center_offset_y="0"/>
			<lens type="fisheye" k1="0" k2="0" k3="0" k4="0"/>
			<fisheye_radius radius_pixels="512"/>
		</optics>
	</camera>
	<camera width="1024" height="1024" layout="equatorial">
		<input_calib_file name="3.jpg"/>
		<pose>
			<rotation yaw_deg="180.000000" pitch_deg="0.000000" roll_deg="0.000000"/>
			<translation x_cm="21.0" y_cm="1.0" z_cm="0.000000"/>
		</pose>
		<optics>
			<focal_length focal_pixels="316.830175"/>
			<principal_point center_offset_x="0" center_offset_y="0"/>
			<lens type="fisheye" k1="0" k2="0" k3="0" k4="0"/>
			<fisheye_radius radius_pixels="512"/>
		</optics>
	</camera>
	<camera width="1024" height="1024" layout="equatorial">
		<input_calib_file name="4.jpg"/>
		<pose>
			<rotation yaw_deg="270.000000" pitch_deg="0.000000" roll_deg="0.000000"/>
			<translation x_cm="4.5" y_cm="23.0" z_cm="0.000000"/>
		</pose>
		<optics>
			<focal_length focal_pixels="316.830175"/>
			<principal_point center_offset_x="0" center_offset_y="0"/>
			<lens type="fisheye" k1="0" k2="0" k3="0" k4="0"/>
			<fisheye_radius radius_pixels="512"/>
		</optics>
	</camera>
</camera_rig>

Can somebody explain which parameter can affect to calibration convergence?

I have encountered the same issue.