NLog & GrowlNotify, added assembly can't be found after deploying - asp.net

Question

I'm using NLog and Growl. It works fine locally. When I deploy the website, I get the error that :
Exception: NLog.NLogConfigurationException: Exception when parsing E:\Websites\SPECIFICATION\NLog.config. ---> System.ArgumentException: Target cannot be found: 'NLog.Targets.GrowlNotify'
But this dll does exist in my bin directory. I added all the required files via nuget.
And my config file:
<?xml version="1.0" encoding="utf-8"?>
<nlog xsi:schemaLocation="http://www.nlog-project.org/schemas/NLog.xsd NLog.xsd" autoReload="true" throwExceptions="false" throwConfigExceptions="true" internalLogToConsole="true" internalLogLevel="Trace" internalLogFile="E:\Websites\SPECIFICATION\App_Data\log.txt" xmlns:p1="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.nlog-project.org/schemas/NLog.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<variable name="myvar" value="myvalue" />
<extensions>
<add assembly="NLog.Targets.GrowlNotify" />
</extensions>
<targets>
<target name="db" xsi:type="Database" connectionString="Data Source=AA;Initial Catalog=BB;User ID=SA;Password=BBBB" connectionStringName="SC" commandType="StoredProcedure" commandText="[dbo].[NLog_AddEntry_p]">
<parameter name="#machineName" layout="${machinename}" />
<parameter name="#siteName" layout="${iis-site-name}" />
<parameter name="#logged" layout="${date}" />
<parameter name="#level" layout="${level}" />
<parameter name="#username" layout="${aspnet-user-identity}" />
<parameter name="#message" layout="${message}" />
<parameter name="#logger" layout="${logger}" />
<parameter name="#properties" layout="${all-event-properties:separator=|}" />
<parameter name="#serverName" layout="${aspnet-request:serverVariable=SERVER_NAME}" />
<parameter name="#port" layout="${aspnet-request:serverVariable=SERVER_PORT}" />
<parameter name="#url" layout="${aspnet-request:serverVariable=HTTP_URL}" />
<parameter name="#https" layout="${when:inner=1:when='${aspnet-request:serverVariable=HTTPS}' == 'on'}${when:inner=0:when='${aspnet-request:serverVariable=HTTPS}' != 'on'}" />
<parameter name="#serverAddress" layout="${aspnet-request:serverVariable=LOCAL_ADDR}" />
<parameter name="#remoteAddress" layout="${aspnet-request:serverVariable=REMOTE_ADDR}:${aspnet-request:serverVariable=REMOTE_PORT}" />
<parameter name="#callSite" layout="${callsite}" />
<parameter name="#exception" layout="${exception:tostring}" />
</target>
<target name="growl" xsi:type="GrowlNotify" password="" host="192.168.1.10" port="23053"/>
</targets>
<rules>
<!-- add your logging rules here -->
<logger name="*" minlevel="Trace" writeTo="db" />
<logger name="*" minLevel="Trace" writeTo="growl" />
</rules>
</nlog>
I'm not sure why it works locally but not on the deployed version. They're the same. And the dll exists on both. Any ideas?
Update:
After enabling binding logging I get these log messages:
Assembly manager loaded from:
C:\Windows\Microsoft.NET\Framework64\v4.0.30319\clr.dll
Running under executable c:\windows\system32\inetsrv\w3wp.exe
--- A detailed error log follows.
=== Pre-bind state information ===
LOG: DisplayName = NLog, Version=2.0.0.0, Culture=neutral, PublicKeyToken=5120e14c03d0593c
(Fully-specified)
LOG: Appbase = file:///E:/Websites/SPECIFICATION/
LOG: Initial PrivatePath = E:\Websites\SPECIFICATION\bin
Calling assembly : NLog.Targets.GrowlNotify, Version=1.0.1.0, Culture=neutral, PublicKeyToken=null.
===
LOG: This bind starts in default load context.
LOG: Using application configuration file: E:\Websites\SPECIFICATION\web.config
LOG: Using host configuration file: C:\Windows\Microsoft.NET\Framework64\v4.0.30319\aspnet.config
LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework64\v4.0.30319\config\machine.config.
LOG: Post-policy reference: NLog, Version=2.0.0.0, Culture=neutral, PublicKeyToken=5120e14c03d0593c
LOG: Attempting download of new URL file:///C:/Windows/Microsoft.NET/Framework64/v4.0.30319/Temporary ASP.NET Files/specification/f65047fd/2d5397dc/NLog.DLL.
LOG: Attempting download of new URL file:///C:/Windows/Microsoft.NET/Framework64/v4.0.30319/Temporary ASP.NET Files/specification/f65047fd/2d5397dc/NLog/NLog.DLL.
LOG: Attempting download of new URL file:///E:/Websites/SPECIFICATION/bin/NLog.DLL.
WRN: Comparing the assembly name resulted in the mismatch: Major Version
ERR: Failed to complete setup of assembly (hr = 0x80131040). Probing terminated.
Is this something to do with nuget not being able to download the latest packages on the production server? But if the error is with NLog.dll why does NLog log to my database just fine, and only growl doesn't work?

Answer 1

NLog.Grow is build to NLog 2. Because NLog is strong named, the strong names should match.
NLog.Web is using NLog 4 and the strong name for all NLog 4.x versions is 4.0.0.0.
To fix these problems, you need a bindingRedirect in your .config:
<dependentAssembly>
<assemblyIdentity name="NLog" publicKeyToken="5120e14c03d0593c" culture="neutral" />
<bindingRedirect oldVersion="0.0.0.0-4.0.0.0" newVersion="4.0.0.0" />
</dependentAssembly>
But please note this isn't 100% safe, as breaking changes could lead to method mismatch errors.