Renaleo

Hi All, I'm based in the UK and usually operate on UK Sites, but at the moment I'm working on a Site Layout for Cape Town. I've inherited a georeferenced DWG from a local contractor and imported it fine into Vectorworks. When I set my Coordinate system to match the DWG (WGS 84 Southern Hemsiphere) I get an error: CPLErr( 3 ), err_no( 1 ) No inverse operation When I try to manually Geolocate the drawing I get the same error. I have no idea what this means, does anybody know hoe to fix it? Thanks!