Parham, there are three visible causes of this issue:
- The first possible cause is the java-script error.
It can occurred if one of the third-party plugins conflicts with Messages plugin which causes the .js error.
You need to enable FireBug console (Mozilla FireFox developers extention) to see if there are any errors.
- The second cause - it might happen because of the custom changes performed in the code. They can cause errors in the Messages plugin functionality. Revert the changes back to see if it solves the problem.
Also, try to enable DEV_MODE to recompile resources (https://docs.oxwall.org/plugin-tuts:enable-debug).
- The last possible cause is the theme your are using. Probably it has some markup problems.
Please try to check if it works for you at our demo site.
If so, try to deactivate all third-party plugins at your site, remove performed code modification and switch the theme to the default one.
One of these options should solve the issue and help to detect which of reason could cause the problem.