Missing services, sapinst fails during Starting Instance phase

Dears,

I'm installing an ERP 605 on Win 2008 R2 with DB2 9.7 FP5. The sapinst fails at the phase Starting Central Services.

The installation is almost finished the load of the database ended successfully.

What I noticed is that at Os level the the Sap windows services are missing, infact into the Sap Management COnsole it's missing completely the instance

tree .

Into the sapinst logs no reason why the windows services are missing. What could be the reason ?

regards