What steps will reproduce the problem?
1. Go to Vendor
2.  Open Vendor
3. Close Vendor
4. Get Error

What is the expected output? What do you see instead?
To show the Sell Button. But on the first open no sell button but after we close the vendor and close the error and re-open vendor button shows up and no error.

What version of the product are you using?
a034

Do you have an error log of what happened?

Date: 2011-01-14 18:04:01
ID: 1
Error occured in: Global
Count: 1
Message: ..\AddOns\SellOMatic2_List\SOM_frames.lua line 116:
   attempt to index field 'ButtonFrame' (a nil value)
Debug:
   (tail call): ?
   SellOMatic2_List\SOM_frames.lua:116 HideButtonFrame()
   SellOMatic2\SOM_main.lua:160 ?()
   ...Ons\Ace3\CallbackHandler-1.0\CallbackHandler-1.0.lua:147
      ...Ons\Ace3\CallbackHandler-1.0\CallbackHandler-1.0.lua:147
   [string "safecall Dispatcher[1]"]:4:
      [string "safecall Dispatcher[1]"]:4
   [C]: ?
   [string "safecall Dispatcher[1]"]:13: ?()
   ...Ons\Ace3\CallbackHandler-1.0\CallbackHandler-1.0.lua:92 Fire()
   Ace3\AceEvent-3.0\AceEvent-3.0.lua:120
      Ace3\AceEvent-3.0\AceEvent-3.0.lua:119
   [C]: CloseMerchant()
   ..\FrameXML\MerchantFrame.lua:54
      ..\FrameXML\MerchantFrame.lua:53
   [C]: Hide()
   ..\FrameXML\UIParent.lua:1451 SetUIPanel()
   ..\FrameXML\UIParent.lua:1527 HideUIPanel()
   ..\FrameXML\UIParent.lua:1202
      ..\FrameXML\UIParent.lua:1194
   [C]: SetAttribute()
   ..\FrameXML\UIParent.lua:1894 HideUIPanel()
   ..\FrameXML\UIParent.lua:1898 HideParentPanel()
   [string "*:OnClick"]:1:
      [string "*:OnClick"]:1
AddOns:
  Swatter, v3.2.3 (<%codename%>)
  Ace3, v
  ACP, v3.3.13
  AddonLoader, v2.0
  AdvancedTradeSkillWindow, v
  Atlas, v1.18.1
  AtlasBattlegrounds, v1.18.1
  AtlasDungeonLocs, v1.18.1
  AtlasOutdoorRaids, v1.18.1
  AtlasTransportation, v1.18.1
  AtlasLoot, vv6.01.02
  AtlasLootBurningCrusade, vv6.01.02
  AtlasLootCataclysm, vv6.01.02
  AtlasLootClassicWoW, vv6.01.02
  AtlasLootCrafting, vv6.01.02
  AtlasLootWorldEvents, vv6.01.02
  AtlasLootWrathoftheLichKing, vv6.01.02
  AtlasQuest, v4.6.0a
  AucAdvanced, v5.9.4960 (WhackyWallaby)
  AucFilterBasic, v5.9.4960 (WhackyWallaby)
  AucFilterOutlier, v5.9.4960.2531
  AucMatchUndercut, v5.9.4960.2531
  AucScanData, v5.9.4960 (WhackyWallaby)
  AucStatHistogram, v5.9.4960 (WhackyWallaby)
  AucStatiLevel, v5.9.4960 (WhackyWallaby)
  AucStatPurchased, v5.9.4960 (WhackyWallaby)
  AucStatSales, v5.9.4960.2842
  AucStatSimple, v5.9.4960 (WhackyWallaby)
  AucStatStdDev, v5.9.4960 (WhackyWallaby)
  AucStatWOWEcon, v5.9.4960.2530
  AucUtilAHWindowControl, v5.9.4960.3311
  AucUtilAppraiser, v5.9.4960.2530
  AucUtilAskPrice, v5.9.4960.3175
  AucUtilAutoMagic, v5.9.4960.3142
  AucUtilCompactUI, v5.9.4960.2530
  AucUtilEasyBuyout, v5.9.4960.3583
  AucUtilFixAH, v5.9.4960 (WhackyWallaby)
  AucUtilGlypher, v5.9.4960.2545
  AucUtilItemSuggest, v5.9.4960.3108
  AucUtilPriceLevel, v5.9.4960.2545
  AucUtilScanButton, v5.9.4960.2530
  AucUtilScanFinish, v5.9.4960.2530
  AucUtilScanProgress, v5.9.4960.2530
  AucUtilScanStart, v5.9.4960.4819
  AucUtilSearchUI, v5.9.4960.3655
  AucUtilSimpleAuction, v5.9.4960.4546
  AucUtilVendMarkup, v5.9.4960.2530
  Babylonian, v5.1.DEV.130
  BindPad, v2.3.7
  Clique, vv40000-1.3.3
  Configator, v5.1.DEV.282
  DamnTooltipIcons, v
  DBMCore, v
  DebugLib, v5.1.DEV.275
  EasyMail, v
  FBTitan, v0.9.9
  FishingBuddy, v0.9.9e3
  flagRSP2, v2.4.4
  Gatherer, v3.2.3
  GearScore, v4.1.02
  GHI, v1.0.0
  GHM, v0.7
  GHU, v0.5
  Grid, v1.40000.1403
  InFlightLoad, v4.0.003
  Informant, v5.9.4960 (WhackyWallaby)
  LibBabbleBoss30, v
  LibBabbleZone30, v
  LibStub, v
  MovableHolyPower, v1.41
  MyRolePlay, v4.0.3.47
  Omen, v3.1.0
  PallyPower, vv4.0.17
  PowerAuras, v4.9
  Quartz, v3.0.4
  RatingBuster, v
  Recount, v
  SellOMatic2, va034
  SellOMatic2Class, va034
  SellOMatic2Destroy, va034
  SellOMatic2Item, va034
  SellOMatic2List, va034
  Stubby, v5.9.4960 (WhackyWallaby)
  TasteTheNaimbow, v
  Titan, v5.0.1.40000 - Revision 485
  TitanBag, v5.0.1.40000
  TitanClock, v5.0.1.40000
  TitanGold, v5.0.1.40000
  TitanLocation, v5.0.1.40000
  TitanPerformance, v5.0.1.40000
  TitanRepair, v5.0.1.40000
  TitanVolume, v5.0.1.40000
  TitanXP, v5.0.1.40000
  TomTom, vv40000-1.0.9
  tullaCC, v2.2b
  XPerl, v3.1.2
  XPerlArcaneBar, v
  XPerlOptions, v
  XPerlParty, v
  XPerlPartyPet, v
  XPerlPlayer, v
  XPerlPlayerBuffs, v
  XPerlPlayerPet, v
  XPerlRaidAdmin, v
  XPerlRaidFrames, v
  XPerlRaidMonitor, v
  XPerlRaidPets, v
  XPerlTarget, v
  XPerlTargetTarget, v
  ZygorGuidesViewer, v3.0
  ZygorTalentAdvisor, v2.0.240
  BlizRuntimeLib_enUS v4.0.3.40000 <us>
  (ck=beb)

Please provide any additional information below.