Select a cable name with a dynamic popupmenu and Position?

Questions
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1

I’m selecting a cable name with a dynamic popupmenu and I’m attempting to determine the position of that cable in cablearray. If I input manually the cable name in quotes I receive the correct position.
How to force Dynamic[u] to return the cable name in quotes?

cablearray = {"Bison", "Bittern", "Bluebird", "Bluejay", "Bluejay_t2",
    "Bobolink", "Brant", "Bunting", "Canary", "Canvasback", 
   "Cardinal", "Chickadee", "Chukar", "Cochin", "Condor", "Coot", 
   "Curlew", "Dipper", "Dorking", "Dotterel", "Dove", "Drake", 
   "Eagle", "Egret", "Falcon", "Finch", "Flamingo", "Flicker", 
   "Gannet", "Grackle", "Grosbeak", "Grouse", "Guinea", "Hawk", "Hen",
    "Ibis", "Kingbird", "Lark", "Leghorn", "Mallard", "Martin", 
   "Merlin", "Minorca", "Orchid AAC", "Oriole", "Ortolan", "Osprey", 
   "Ostrich", "Parakeet", "Partridge", "Peacock", "Pelican", 
   "Penguin", "Petrel", "Pheasant", "Pigeon", "Quail", "Rail", 
   "Raven", "Redwing", "Robin", "Rook", "Ruddy", "Sparate", "Sparrow",
    "Squab", "Starling", "Stilt", "Swan", "Swanate", "Swift", "Teal", 
   "Tern", "Turkey", "Waxwing"};

{PopupMenu[Dynamic[u], cablearray], Dynamic[u]}

Position[cablearray, Dynamic[u]]
2

Try wrapping the whole query in Dynamic:

Dynamic[Position[cablearray, u]]
3

This work very nicely and gives the cable name in quotes. Thanks. I’m still quite new to Mathematica.

That said, I’m not sure how to clear the error: Part::pkspec1: The expression ?? cannot be used as a part specification. Generated by code below. I’ve reviewed the many other replies to this simple question, but remain stumped.

sccdata = {{"ACCR_558-T73", 0.`, 31378.`, -17629.9`, -6893.`, 
    3574.`}, {"Bison", -472.6`, 52971.8`, -51954.7`, 13720.`, 
    6138.`}, {"Bittern", -1012.4`, 64046.`, -50768.6`, -27693.`, 
    39210.`}, {"Bluebird", -1237.2`, 64355.7`, -63104.2`, 5109.`, 
    15764.`}, {"Bluejay", -1012.4`, 64046.`, -50768.6`, -27693.`, 
    39210.`}, {"Bluejay_t2", -1012.4`, 64046.`, -50768.6`, -27693.`, 
    39210.`}, {"Bobolink", -1012.4`, 64046.`, -50768.6`, -27693.`, 
    39210.`}, {"Brant", -1653.6`, 71375.3`, -82065.9`, 20811.`, 
    13436.`}, {"Bunting", -1012.4`, 64046.`, -50768.6`, -27693.`, 
    39210.`}, {"Canary", -472.6`, 52971.8`, -51954.7`, 13720.`, 
    6138.`}}  cablearray = {"Bison", "Bittern", "Bluebird", "Bluejay", "Bluejay_t2",
        "Bobolink", "Brant", "Bunting", "Canary", "Canvasback", 
       "Cardinal", "Chickadee", "Chukar", "Cochin", "Condor", "Coot", 
       "Curlew", "Dipper", "Dorking", "Dotterel", "Dove", "Drake", 
       "Eagle", "Egret", "Falcon", "Finch", "Flamingo", "Flicker", 
       "Gannet", "Grackle", "Grosbeak", "Grouse", "Guinea", "Hawk", "Hen",
        "Ibis", "Kingbird", "Lark", "Leghorn", "Mallard", "Martin", 
       "Merlin", "Minorca", "Orchid AAC", "Oriole", "Ortolan", "Osprey", 
       "Ostrich", "Parakeet", "Partridge", "Peacock", "Pelican", 
       "Penguin", "Petrel", "Pheasant", "Pigeon", "Quail", "Rail", 
       "Raven", "Redwing", "Robin", "Rook", "Ruddy", "Sparate", "Sparrow",
        "Squab", "Starling", "Stilt", "Swan", "Swanate", "Swift", "Teal", 
       "Tern", "Turkey", "Waxwing"};
    (*Make pop up menu to select conductor*)
    cables = {PopupMenu[Dynamic[u], cablearray], Dynamic[u]}
    (*Get row number for conductor, clear out brackets*)
    cableloc = Dynamic[First[Flatten[Position[cablearray, u]]]]
    (*Define table for coefficients*)
    a = Table[0, {i, 1, 5}]
    i = 1;
    (*Attempt to fill table with cable coefficients*)
    Do[
      a[[i]] = sccdata[[cableloc, i + 1]];
      i = i + 1;
      , 5]; ;