I need a quick help opencart!

I have purchased a custom theme and installed it properly on my main domain. Now I did like to have the features of Multistore, so I have created a subdomain and assigned the custom theme under settings and theme. I am able to see the theme under subdomain now but the theme is not working properly. When I'm trying to access the second store to configure the theme in the custom theme module, it is showing an error like "You do not have permission to access this page, please refer to your system administrator.". I have checked the user group and everything is checked. I also noticed the following path change when accessing the first store and the second store etc