RRD problem with a Custom Script

Try changing this line:

 
NCV_rb-conn =3D "Heildartegngingarfr:GAUGE"

 
To:

 
NCV_rb-conn =3D "*:GAUGE"

 
Your rrd file says that its of type DERIVE, and not gauge.. that will

(should) fix it.

 
You should delete the rrd file after making the change, and rerun the
check.. see if it creates a rrd of the GAUGE type after that