Shortcode a shortcode

For repeatable sections of my site pages i try to use shortcodes so that i only need to edit the content 1 time. I have found a problem though and dont know how to solve it.

Whenever I put content that is a shortcode it does not do what it suposed to in the site.

Ex I use the membership plugin and I use the Access level shortcodes to show content to people based on their access. Whenever I try to turn that into a shortcode it seems to break the functionality of the Access-Level shortcode.

Code in the webpage:
[level-user]content I want to show members of the users access level[/level-user]

Code in functions.php to shortcode the above:

function UserContentShortcode() {
return '[level-user]content I want to show members of the users access level[/level-user]';
}
add_shortcode('UserContent', 'UserContentShortcode');

Shortcode added to the web page:
[UserContent]

When Logged in as a User I see this on the page:
[level-user]content I want to show members of the users access level[/level-user]

This is what I should see:
content I want to show members of the users access level.

I dont have the programming background to understand what I need to be done. Anyone have some insight on what is happeneing/how to fix it?