How to install / use ImageCropper?

Hey guys,

I installed Umbraco and trying to figure out how to use image cropper.

I don't actually know where to start.

When I add a new property of ImageCropper type to my Document type in Settings and then go to Content and click a node of this document type I'm getting a null reference exception straight away with this stck trace:

[NullReferenceException: Object reference not set to an instance of an object.]
   umbraco.editorControls.imagecropper.DataEditor.OnInit(EventArgs e) +842
   System.Web.UI.Control.InitRecursive(Control namingContainer) +132
   System.Web.UI.Control.InitRecursive(Control namingContainer) +420
   System.Web.UI.Control.InitRecursive(Control namingContainer) +420
   System.Web.UI.Control.InitRecursive(Control namingContainer) +420
   System.Web.UI.Control.InitRecursive(Control namingContainer) +420
   System.Web.UI.Control.AddedControl(Control control, Int32 index) +276
   umbraco.controls.ContentControl.addControlNew(Property p, TabPage tp, String Caption) +3675
   umbraco.controls.ContentControl.CreateChildControls() +1723
   System.Web.UI.Control.EnsureChildControls() +181
   umbraco.controls.ContentControl.OnInit(EventArgs e) +122
   System.Web.UI.Control.InitRecursive(Control namingContainer) +132
   System.Web.UI.Control.AddedControl(Control control, Int32 index) +276
   umbraco.cms.presentation.editContent.OnInit(EventArgs e) +1004
   System.Web.UI.Control.InitRecursive(Control namingContainer) +132
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1969

So I thought may be I need to install ImageCropper package first. When I go to Package repository and try to install ImageCropper package I'm getting this error:

Error - file not found. Could find file named 'C:\www\Umbraco4.7\App_Data\'

and the stack trace is: 

[Exception: Error - file not found. Could find file named 'C:\www\Umbraco4.7\App_Data\']
   umbraco.cms.businesslogic.packager.Installer.Import(String InputFile) +651
   umbraco.presentation.developer.packages.Installer.Page_Load(Object sender, EventArgs e) +941
   System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +25
   umbraco.BasePages.BasePage.OnLoad(EventArgs e) +19
   System.Web.UI.Control.LoadRecursive() +71
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +3064

This is defenitely a correct path and I do have App_Data folder. 

I tried to install another package (ImageGen) and it was installed fine without any problems.

So, what am I doing wrong and where to start?

Thank you