Failed to create graph with error code 1

[Cojo]

First i got the error:
Failed to create graph with error code 1, the error is: ERROR: No DS called 'qwanRoot' in '/var/db/rrd/wan-queues.rrd'

I searched the forum and found this thred.
I did as it said there but now i get the following error instead.

Failed to create graph with error code 1, the error is: ERROR: reading the cookie off /var/db/rrd/wan-queues.rrd faild

[sullrich]

(corrected)

Run this from a shell:

rm /var/db/rrd/wan-queues.rrd

Then reboot.