CelticSignalStorm vs. AAE, holdviolations

Hi there,

we are using Encounter 13.1 and changed the from SignalStorm flow to AAE flow.
While porting our scripts we found out, that even if AAE optimizes the design and fixes all hold violations,
SignalStorm still finds hold violations. So is SignalStorm more pessimistic?
We now use the following script for postRoute optimization:

...
setAnalysisMode -analysisType onChipVariation -cppr both
setDelayCalMode -SIAware true -engine default

# In-Place-Optimization
setOptMode -usefulSkew true

#step -> optimizatzion effort

for {set step 0} {$step <= $Effort} {incr step} { 
    if {$step==0} {
        optDesign -postRoute
       if { $::SOC_FIX_HOLD == 1 } {
           optDesign -postRoute -hold
           }
       } else {
           optDesign -postRoute -incr
           if { $::SOC_FIX_HOLD == 1 } {
               optDesign -postRoute -hold -incr
               }
       }
}

#switch engine to use slow but more accurate Signal Storm optimization
#for setup and hold optimization with signal integrity optimization enabled

setDelayCalMode -engine signalStorm -SIAware false
optDesign -postRoute
if { $::SOC_FIX_HOLD == 1 } {
    optDesign -postRoute -hold
    }
if { $::SOC_FIX_HOLD == 1 } {
    optDesign -postRoute -hold -si
   }
optDesign -postRoute -si
}

So our question is, why are there still hold violations using AAE for optimization and SGS for timing analysis?
Is our flow the right way or do you have any suggestions for handling this issue ?

Kind regards,
Marten