Please provide more detailed information such as which logo you tried ? and is it happening with all the logos ?
Also mention which software you are trying to open the EPS file in, the more the information we receive the easier it would be to solve your problem.
Email the EPS file to the SignLab company, i'm sure they will update you on the exact specifics of the issue.
Since i don't have nor have used SignLab so can't help you out further, since most of the folks here.. use Adobe Illustrator and EPS works great there :)