Looking up a value in a list & returning multiple corresponding va

[Bob]

Complete Subject: Looking up a value in a list & returning multiple
corresponding values in an in-cell dropdown

Column A = list of Program numbers
Column B = list of Project numbers

For a given Program number there can be one or more Project numbers.
Consequently, Column A contains duplicate Program numbers.

Cell C1 = a user inputs a Program number
Cell D1 = I would like to display an in-cell dropdown with the list of
Project numbers associated with the inputted Program number in cell C1

I looked at a potential solution I found at
http://office.microsoft.com/en-us/excel/HA012260381033.aspx?pid=CL100570551033#backtotop.
Using a named range, I can get the results to appear in an in-cell dropdown.
However, since the number of results will vary by Program number, I have not
been able to figure out how NOT to display "blank" results in the in-cell
dropdown.

For example, if I create a four-cell named range, but the number of results
(i.e., Project numbers) for a given Program number is only two, the in-cell
dropdown displays the two Project numbers as well as two blank "placeholders".

Any help would be greatly appreciated.

Thanks,
Bob

 

[Bob]

Thanks for your help. Unfortunately, the in-cell dropdown is still showing
blank entries when the results are less than 4 Project numbers, which is the
total number of cells I needed to copy the following formula:

{=IF(ISERROR(INDEX($A$1:$B$7,SMALL(IF($A$1:$A$7=$A$9,ROW($A$1:$A$7)),ROW(1:1)),2)),"",INDEX($A$1:$B$7,SMALL(IF($A$1:$A$7=$A$9,ROW($A$1:$A$7)),ROW(1:1)),2))}

Note: there can be up to 4 Projects for a given Program.

I welcome any other suggestions.

Thanks again,
Bob