AVERROR code on avfilter_graph_config

When I use:

avfilter_graph_config(filter_graph, NULL)

it fails and returns -22. The documentation states that if it fails it
returns a negative AVERROR code, but I can't find documentation anywhere
that tells me what the code -22 actually means.

I can successfully parse the graph beforehand:

filter_descr = "movie=logo.png [logo];[in][logo]
overlay=10:main_h-overlay_h-10 [out]"
avfilter_graph_parse(filter_graph, filter_descr, &inputs, &outputs, NULL)

but I avfilter_graph_config does not work.

As a side note, it does work if I use 
filter_descr = "color=red <at> 0.2:720x480:10 [color]; [in][color] overlay [out]"

I have made sure that I have enabled the overlay and movie filters when I
compiled FFmpeg.

What does the return value -22 mean? For what reasons will
avfilter_graph_config fail when using that filter_desc?

Cheers,

--
View this message in context: http://ffmpeg-users.933282.n4.nabble.com/AVERROR-code-on-avfilter-graph-config-tp4374534p4374534.html
Sent from the FFmpeg-users mailing list archive at Nabble.com.