Packaging error, using Widget Menu

Hello,

I have problem with my Pause Menu. I`m using Widget named Menu. I create widget in the FirstPersonCharacter blueprint. I have resume button in Menu. Compile it, everything is ok, no errors. Play game, everything works fine, still no error after exit. Save all and reopen project. I get error about Menu. I go to Menu, compile and everything is ok. Play, everythin works. I get this error everytime I open the project. And the main reason I am writing this post is, that Package failed because of this Menu (Windows 64bit).

UATHelper: Packaging (Windows (64-bit)): Program.Main: AutomationTool exiting with ExitCode=25 (Error_UnknownCookFailure)
UATHelper: Packaging (Windows (64-bit)): BUILD FAILED
PackagingResults:Error: Error Unknown Cook Failure

I am using Windows 10, 64bit, UE 4.15, did not switch between versions.

I dont understand, how it`s possible, that everything works fine in editor Play, but get error after opening projcet and Packaging.

136604-2017-05-03_09-40-10.jpg

136605-2017-05-03_09-40-39.jpg

UATHelper: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2017.05.03-07.43.05:736][ 0]LogInit:Display: LogBlueprint:Warning: [Menu] ‘Slider_2’ variable not found. Base class was probably changed.

UATHelper: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2017.05.03-07.43.05:736][ 0]LogInit:Display: LogBlueprint:Warning: [Menu] ‘Slider_6’ variable not found. Base class was probably changed.

UATHelper: Packaging (Windows (64-bit)): UE4Editor-Cmd: [2017.05.03-07.43.05:736][ 0]LogInit:Display: LogBlueprint:Warning: [Menu] ‘Slider_18’ variable not found. Base class was probably changed.