Basic Excel If Logic Question

I have a worksheet that I made for some manufacturing supervisors to use to plan their work out.

There are a few different machines that I have in a data validation drop down box in cell B9 (referenced below). They call to a table named "Standards" that has the machine names and default performance results we expect when we don't know the intricacies of a new product.

For each machine, I have a lookup table (with defined name nomenclature= _Mach#Standards, e.g. _124Standards). The lookup table gives us the different job names that run on each machine and their specific expected performance results.

On the worksheet, once the supervisor chooses the machine (Ex. 124) the next box below it in B11 uses the indirect function ("_"$B9) to list the job names which they can choose from the _124 table. Based on which job name they choose, the rest of the spreadsheet will populated expected instantaneous speeds, hourly targets, waste targets, etc.

However, if they do not choose a job name, I would like the formula to notice that B11 is blank and then do a vlookup of the machine in the default "Standards" table.

You can see my logic below using nested if statements. I thought that using the last argument "VLOOKUP(B9,Standards,2,FALSE)" would tell excel "If everything has been false thus far, use this equation." However, Excel still returns a #N/A.

Any ideas? Thanks!

=IF(B9=124,VLOOKUP($B$11,_124Standards,2,FALSE),IF(B9=125,VLOOKUP($B$11,_125Standards,2,FALSE),IF(B9=127,VLOOKUP($B$11,_127Standards,2,FALSE),IF(B9=131,VLOOKUP($B$11,_131Standards,2,FALSE),IF(B9=135,VLOOKUP($B$11,_135Standards,2,FALSE),VLOOKUP(B9,Standards,2,FALSE))))))