Private Plurk Not Received

A friend sent a Private Plurk to her friends which I did not receive.
I know this, because another friend who shares a house with me also has the same friend. The house friend told me about her private message. I wrote to her on the PP, using my friend's account. She replied, sending me the url of the PP, asking me to open my account and paste it in using that.

When I did so, I received a message saying I did not have permission to view the Plurk, as it is only viewable to her friends.

She is on my friend's list, and she is on mine.

When she sends me a one-to-one PP, I receive it.

Regards,

andavane