Failed to reference NinjaTrader.Custom

[gg80108]

Was looking for something else and found this is the log.. How do i go about fixing this message?
2010-12-27 09:38:58:145 Code.Editor.OnLoad: Failed to reference 'NinjaTrader.Custom, Version=7.0.1000.1, Culture=neutral, PublicKeyToken=null': System.IO.FileNotFoundException: The specified module could not be found. (Exception from HRESULT: 0x8007007E)
at System.Reflection.Assembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, Assembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection)
at System.Reflection.Assembly.InternalLoad(AssemblyNa me assemblyRef, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection)
at System.Reflection.Assembly.LoadFrom(String assemblyFile)
at NinjaTrader.Code.Editor.OnLoad(Object sender, EventArgs e)

Enclosed the reference from the editor but didn't see anything here..

[NinjaTrader_RyanM1]

Hello gg80108,

We identified a scenario that caused this error - compiling during a backtest. This message can be safely ignored and for now we recommend not compiling during a backtest or optimization.