checklink: errors robots txt

Dear Sirs,

My compliments for your work and the free services you offer.

I think there is abug to report. During link checker of www.limotaxi.net/linksaspx  i received the following:
>>
The link was not checked due to robots exclusion rules. Check the link manually, and see also the link checker documentation on robots exclusion.
500 1 This is a server side problem. Check the URI.
>>

though my robots.txt does not have exclusion rules.

I hope to be helpful
Regards Vasilis