It is not possible to convert individual files from VMware virtual machines between themselves, in this case vmx to vmdk conversion. What you can do however is to convert whole virtual machines, or for example virtual hard drives. But VMX format is used to store configuration data, which you can at best duplicate only.
This conversion entry was verified by us and conversion was flagged as wrong or not possible.
Usually this happens when the conversion would try to convert different types of data between each other, such as audio to image, or it is not possible because incompatibility between programs, caused by closed file formats, very limited support etc.
If you find entry that you feel is flagged as bad wrongly, please tell us in the discussion below with as much as information as possible so we can fix it.