Error message when uploading contacts

Hi!!

I am trying to upload a new contact list with a TXT unicode file. all works fine, the headers are OK and i dont receive any alert message when uploading the file. However when the upload is running ant the end the pending task bar changes to red and says error. The task ends without uploading the contacts, but i dont know what the error is and how to fix it.

has anyone had the same issue?? how can i fix it?

Thanks