VBA CODED SOLVER : ERROR MESSAGE

[DAGUET]

Dear VBA Experts,
I have been working on this portfolio optimization for a while and everything went fine until I decided to prompt Solver from VBA and determining a constraint. When activated, this constraint cant execute and produce an error message (see attached). this specifically happens when I click on the 'CREATE EFFICIENT FRONTIER' button.
Any help or explanation where that could come from?
Thanks and Best Regards

 

[Hui]

Change the : Sub SolverStDev()
To:

Function SolverStDev()

' SolverStDev Macro
' Solver Min Standard Dev
'
' Keyboard Shortcut: Ctrl+Shift+D
SolverOk SetCell:="$C$48", MaxMinVal:=2, ValueOf:=0, ByChange:="Weights", _
  Engine:=1, EngineDesc:="GRG Nonlinear"
  SolverAdd CellRef:="SumWeights", Relation:=2, FormulaText:="1"
  SolverAdd CellRef:="Weights", Relation:=3, FormulaText:="0"
  SolverAdd CellRef:="$B$48", Relation:=2, FormulaText:="TargetReturn"
SolverOk SetCell:="$C$48", MaxMinVal:=2, ValueOf:=0, ByChange:="Weights", _
  Engine:=1, EngineDesc:="GRG Nonlinear"
   
  SolverStDev = Application.Run(SolverSolve, True)
End Function

 

[DAGUET]

Hui
as always great job from you
many many thanks it works
I appreciate a lot
warmful day to you
all the best

Change the : Sub SolverStDev()
To:

Function SolverStDev()

' SolverStDev Macro
' Solver Min Standard Dev
'
' Keyboard Shortcut: Ctrl+Shift+D
SolverOk SetCell:="$C$48", MaxMinVal:=2, ValueOf:=0, ByChange:="Weights", _
  Engine:=1, EngineDesc:="GRG Nonlinear"
  SolverAdd CellRef:="SumWeights", Relation:=2, FormulaText:="1"
  SolverAdd CellRef:="Weights", Relation:=3, FormulaText:="0"
  SolverAdd CellRef:="$B$48", Relation:=2, FormulaText:="TargetReturn"
SolverOk SetCell:="$C$48", MaxMinVal:=2, ValueOf:=0, ByChange:="Weights", _
  Engine:=1, EngineDesc:="GRG Nonlinear"
  
  SolverStDev = Application.Run(SolverSolve, True)
End Function