How to print a duration

[FredZwarts]

I made a graph for the remaining run-time of the UPS. This works very well with the Left Axis Formatter set to Duration. It shows the remaining run-time in the format '0:41:21'.
Now I would like to use the same format in the GPRINTs of the graph. I made a preset GPRINT, using the format specifications described in https://oss.oetiker.ch/rrdtool/doc/rrdg ... html#PRINT for a duration. I use a CDEF to convert the values to milliseconds. but it seems that it does not recognize formats like %H, %m and %s. The graph only shows: 'Unknown RRDtool error'.
I am confused because the same specifiers are described for time values.
Is there somewhere an explanation in more detail of how to print a number as a duration, preferably with examples?

[TheWitness]

Are you sure those formatters are supported in RRDtool?

Looks like they are, but what version of RRDtool are you using?

[FredZwarts]

In fact I did not try to use the rrdtool directly, but I tried to create a GPRINT cacti. I did not verify that they are supported.
I have cacti version 1.2.16+ds1-2+deb11u1 with rrdtool 1.7.2-3+b2 installed.
The document I referred to does not mention a version since when these specifiers are supported, so I assumed that they were supported in all versions.

[TheWitness]

There is another post like this. What's likely best is to use a GPRINT Prefix and apply that to the Data Source or the VDEF.