I'm sorry to hear you're having an issue with the detergent dispenser on your DMT300RFS. Please click on the link below then select "Troubleshooting ► Cleaning Performance ► Detergent Is Not Dispensing Properly": http://support-us.samsung.com/cyber...
I would also suggest checking your water pressure and temperature to ensure they are set correctly to effectively dissolve the detergent and clean the dishes. The supplied water pressure should be between 20 and 120 psi, and the temperature should be at least 120˚F.
If these suggestions do not help to resolve the issue, please use the service request link provided in the troubleshooting article for further assistance.