Hi - We have also faced the same issue with SUM1.0 patch 16 SP7 . We solved the issue after following the below steps .
Step 1 : register Host agent with SUM
cd /usr/sap/<SID>/SUM
./STARTUP confighostagent <SID>
Step 2: Restart the SAP Host Agent using the following commands:
cd /usr/sap/<SID>/SUM
<HOSTAGENT directory>/exe/saphostexec -restart
Step 3: Open a web browser window and in the address bar, enter the following URL:
https://<hostname>:1129/lmsl/sumabap/<SID>/doc/sluigui
OR , If the SSL has not been configured, use http instead of https at the beginning of the URL and use port 1128:
http://<hostname>:1128/lmsl/sumabap/<SID>/doc/sluigui
Step 4 :In the dialog box that appears, enter the user name <sid>adm and the password.
Thanks ,
Harsh