Why can't Solver solve my one-variable query, when Goal Seek can?

[Mike Wilcox]

I wrote a little routine to determine buy/sell amounts to achieve my asset allocation targets. I wanted to give it more functionality by back-calculating allocations based on which securities I hold.

So I started by using Solver to do the same solution that Goal Seek already does, figuring that after that I could add other constraints and variables. Problem is that Solver can't find the solution that Goal Seek does readily. Any idea why?

 

[Myrna Larson]

Not without seeing your layout and what you typed in the boxes in the Solver
dialog.

I wrote a little routine to determine buy/sell amounts to achieve my asset

allocation targets. I wanted to give it more functionality by
back-calculating allocations based on which securities I hold.

So I started by using Solver to do the same solution that Goal Seek already

does, figuring that after that I could add other constraints and variables.
Problem is that Solver can't find the solution that Goal Seek does readily.
Any idea why?

 

[Mike Wilcox]

Sorry to be such a dunce, but how do I send you the file? There is no "insert file" option like there is in Outlook.

 

[Jerry W. Lewis]

She didn't invite you to send her a file, she invited you to send to
this thread a detailed description of what you did.

Jerry

 

[Mike Wilcox]

I wrote a one page routine that enables me to input actual current
allocations among bonds, stocks, real estate, precious metals and cash. Then
I input the ratios I want such as 60-40 stocks vs. bonds and 1-1-1 large
caps-small caps-int'l stocks. Then I choose which of several macros to run
that are simply goal seeks for 5%, 10% or 15% cash, and it gives me a perfect
solution every time.

So I tried to do the same calcs with Solver. For "Set Target Cell:" I put
in the cell where the calculated cash percentage is displayed. For "Equal
to: Value of:" I put in 0.05 to solve for 5% cash. For "By Changing Cells:"
I entered the cell from which the model calculates all of the target
allocations.

If use the cash % that is already calulated it says: "Solver found a
solution. All constraints and optimality conditions are satisfied." But if
I enter a cash % that is different, it says, "Solver could not find and
feasible solution."

If I immediately Goal Seek for the same parameters, it gets a solution easily.

Any idea why Solver won't work in this case?

Mike Wilcox