Here are some tips to help you solve the Samsung S-beam issue
1. Restart the Galaxy S4.
2. If on a custom rom, clear dalvik wipe cache.
3. Do a factory reset if necessary.
4. Download AirPush to detector to see if you have any malware apps that may be causing the issue with the S-Beam.
5. Uninstall any suspicious or bad apps.
6. Toggle the switch of the S-Beam app. Menu Button > Settings > More Settings > Select S-Beam and tap it off and on again.