UnityException: cross compilation failed

Hey guys/girls we need your help!,

Whenever I try to build for iOS I get this error

Cross compilation job System.Data.dll failed.
UnityEngine.UnityException: Failed AOT cross compiler: C:/Program Files (x86)/Unity/Editor/Data/BuildTargetTools/iPhonePlayer\mono-xcompiler.exe --aot=full,asmonly,nodebug,static,outfile=“System.Data.dll.s” “System.Data.dll” current dir : C:\Users\Feiko.Feiko-Laptop\Documents\MME\Monster Medical Emergencies v2.0 - 11-04-2014\Temp/StagingArea/Data/Managed
result file exists: False

We need our System.Data.dll to read our database.
Is it possible unity has problems whenever you use .net things in your code?

If so, what is the best way to reach your database on iOS then?
If we build on Android everything goes well and we have no errors.

Does anyone know how to help us?

You cannot make a build for iOS on Windows (you need a Mac). Someone correct me if I am wrong, but I think that is the problem.