Please make sure that you follow below steps:
1/ Download the package from themeforest.net (the file is in zip format)
2/ Extract the file you've just downloaded.
3/ Find the file in the unzipped folder "themes": velatheme_version_package_v1.x.x.zip, then you just need to upload this file to your Shopify store.
1/ Create a staff account for us (with Themes permission and Settings permission) http://docs.shopify.com/manual/settings/account/staff-members
2/ Capture screenshot or video for the issue you get.
3/ Specify which template and version you are using.
4/ Describe clearly how to reproduce the issue.
5/ Send all information (staff account, screenshot, video, template name and version, description of the issues, link) to email@example.com