Isodraw Version problem with .igs models

When i open an .igs model in Isodraw cadprocess 7.0 (at client location), all the parts of an assembly are visible. But, when i open the same .igs model in Isodraw 6.1 or 7.3 cadprocess , there is some dataloss i.e., some parts are not visible or missing. Can anyone explain me what might be the problem or do i need to reinstall the softwares or are there are any plug-ins missing.

Q-2: And also when i open the .wrl files, i am not able to zoom properly and there is a huge dataloss when i onvert to 2d .iso file.

Thanks in advance.