Problems building APK after updating Android SDK

I am running two versions of Unity. Unity 3.5.6 and Unity 5.0.0

I am using the older version of Unity for a project that needs to stay in that version so it doesn’t break.

After installing Unity 5 and trying to build I had an Error that needed me to update the Android SDK So I did this.

Now I am able to build an APK in Unity 5 but not in Unity 3, I receive this Error:

Error building Player: Win32Exception: ApplicationName=‘C:/Program Files (x86)/Android/android-sdk/platforms/android-21\aapt.exe’, CommandLine=‘package -v -f -m -J gen -M AndroidManifest.xml -S “res” -I “C:/Program Files (x86)/Android/android-sdk/platforms/android-21\android.jar” -F bin/resources.ap_’, CurrentDirectory=‘Temp/StagingArea’

I have tried to install a previous version of the Android SDK but the problem is still there and I am unable to build in Unity 3 as I used to be able to do.

I have tried the suggestion of finding the zipaling.exe file and copying it into the sdk/tools folder but that hasnt worked.

Would anyone have any idea of how to go abut resolving this issue so I can build an APK on Unity 3 and Unity 5

Use the r21 version of the sdk.
You can get it here https://dl.google.com/android/android-sdk_r21-windows.zip