svn update issue (how to avoid update before commit in multi user repository)

[sup...@sablostudio.com]

 hi

 i am using svn server from 3-4 years as 1 user per repository. now  working on a repository with 5 designers and developers they all working on same project, designer 1 commit successfully but when designer 2 or 3 trying to commit it ask for update before commit, and when they click on update designers 2 working finished and whole project is updated as designer 1 commit. how to solve this issue (unity collaborate services working fine and never ask for update before commit ) how to avoid update before commit in multi user repository ???????????????????????????????????????????????????????????????????????????????????