Read the users manuel of your program. The size of your GedCom file should be smaller than 2 Mb. I sent a zipp file, but it has not been taken into account. Verify that this file has only one document and that it complies with the formats accepted by GeneaNet. Check that the file is not protected by a password If you have a Macintosh, compress your file into a .zip format.
Different software has a different presentation of dates.
In order to manage properly these differences you can precise the format used by your usual software. I do not manage to update my tree even if i am in wizard mode. Verify that you have not restricted the update by using wizard on your configuration page. In that case you have to create as many different GeneaNet accounts as you have gedcoms to present. You can specify this field so that only people with password will have an access to this data.