Can't run a managed custom action on uninstall

I have a custom action which should be run on uninstall. But for unknown reason the msiexec says "There is a problem with this Windows Installer package. A DLL required for this install to complete could not be run. Contact your support personnel or package vendor.". The code goes below:

<Binary SourceFile="SetupWiX.CA.dll" Id="Binary1"  />       
<CustomAction Id="DropDatabase" BinaryKey="Binary1" DllEntry="DropDatabase" Execute="deferred" Return="check"/>
<Custom Action='DropDatabase'  After="SetCustomActionDataValue_DropDat开发者_StackOverflow社区abase">Installed</Custom>

I have few other custom actions that run on install and they run fine. Everything is same there except the conditions. So how can I make my custom action run on uninstall correctly? I've created a blank wix setup project, and a simple custom action that shows message box on uninstall, and it works fine. I don't know what is the problem with my first custom action. I use the same DLL on install and uninstall. The error log goes below:

Action start 16:07:34: INSTALL.
Action start 16:07:34: ValidateProductID.
Action ended 16:07:34: ValidateProductID. Return value 1.
Action start 16:07:34: CostInitialize.
Action ended 16:07:34: CostInitialize. Return value 1.
Action start 16:07:34: FileCost.
Action ended 16:07:34: FileCost. Return value 1.
Action start 16:07:34: CostFinalize.
Action ended 16:07:34: CostFinalize. Return value 1.
Action start 16:07:34: InstallValidate.
Action ended 16:07:34: InstallValidate. Return value 1.
Action start 16:07:34: InstallInitialize.
Action ended 16:07:37: InstallInitialize. Return value 1.
Action start 16:07:37: ProcessComponents.
Action ended 16:07:37: ProcessComponents. Return value 1.
Action start 16:07:37: UnpublishFeatures.
Action ended 16:07:37: UnpublishFeatures. Return value 1.
Action start 16:07:37: RemoveFiles.
Action ended 16:07:37: RemoveFiles. Return value 0.
Action start 16:07:37: InstallFiles.
Action ended 16:07:37: InstallFiles. Return value 1.
Action start 16:07:37: DropDatabase.
Action ended 16:07:37: DropDatabase. Return value 1.
Action start 16:07:37: RegisterUser.
Action ended 16:07:37: RegisterUser. Return value 0.
Action start 16:07:37: RegisterProduct.
Action ended 16:07:37: RegisterProduct. Return value 1.
Action start 16:07:37: PublishFeatures.
Action ended 16:07:37: PublishFeatures. Return value 1.
Action start 16:07:37: PublishProduct.
Action ended 16:07:37: PublishProduct. Return value 1.
Action start 16:07:37: InstallFinalize.
CustomAction DropDatabase returned actual error code 1154 (note this may not be 100% accurate if translation happened inside sandbox)
MSI (s) (D4:DC) [16:07:41:650]: Product: MyProduct -- Error 1723. There is a problem with this Windows Installer package. A DLL required for this install to complete could not be run. Contact your support personnel or package vendor.  Action DropDatabase, entry: DropDatabase, library: C:\Windows\Installer\MSI4DEF.tmp 

Error 1723. There is a problem with this Windows Installer package. A DLL required for this install to complete could not be run. Contact your support personnel or package vendor.  Action DropDatabase, entry: DropDatabase, library: C:\Windows\Installer\MSI4DEF.tmp 
Action ended 16:07:41: InstallFinalize. Return value 3.
Action ended 16:07:42: INSTALL. Return value 3.

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The problem was in my custom action method being private, not public.