[Plugin: Pagerank tools] Do not update values "n/a"

Hi,
the plugin seems to be installed ok, but I got this message on the plugins page when activated:
The plugin generated 192 characters of unexpected output during activation. If you notice “headers already sent” messages, problems with syndication feeds or other issues, try deactivating or removing this plugin.

Then at pagerank tools page shows a list with all my urls but without values and never was updated.
Like this

n/a	https://www.netmdp.com/tag/wpematico/	[visit]	tag	n/a
n/a	https://www.netmdp.com/	                [visit]	home	n/a

I checked the two tables
wp_prtools_url have all urls

ID 	entrydate 	lastupdate 	url_type 	url 	pr
66 	1294838474 	0 	tag 	https://www.netmdp.com/tag/wpematico/ 	-1
67 	1294838474 	0 	home 	https://www.netmdp.com/ 	-1

wp_prtools_pr is empty

I have a multisite wordpress 3.0.4 installed.

If you plan to fix this and if I can do something for help, let me know.

Thank you very much