You'll have to export your artwork to a different format, such as EPS, Adobe Illustrator or perhaps DXF. The choice will be determined on how Flexi imports each of the format flavors exported.
Software incompatibility is one of the major reasons why I tend to double up designs in at least two apps (typically Corel and Flexi). If you're using an application that suddenly stops getting developed your legacy files could become worthless in a short amount of time. For elaborate, original pieces of vector artwork and original logo designs, I'll archive the finished design in several formats.