If you can't configure the phone using automated settings, then access the AccessPoint Names section and enter the details manually. Use the following settings to activate the Internet connection.
Manual settings.
Profile Name: MTN
Homepage: mtn.co.ug/mobile
Proxy: Enable
Proxy address:10.120.0.138
Proxy port: 8080
APN (Access Point Name): yellopix.mtn.co.ug
Session mode: Permanent
Username :
Password :
Configure it exactly as it appears above. For Username and Password, leave the fields blank.