Issue adding some non dev .dll files to a WiX Installer

I'm fairly new to WiX and I have been trying to create an installer for some software my team has been working on. The installer worked well until the customer asked us to include some of their own .dll files in the installer, up to this point we had left them out as they were to update and install the files themselves. As far as I can tell their .dlls are sound.

Once I had added components to the installer, it would no longer build stating that: "The assembly file 'C:... Some.dll' appears to be invalid. Please ensure this is a valid assembly file and that the user has the appropriate access rights to this file. More information: HRESULT: 0x80131018 (LGHT0132)". Here is how I have added the file incase thats where I am slipping up;

<Component Id="SomeDll" Guid="<GUID>" DiskId="1">
    <File Id="some.dll" Name="some.dll" Source="..\..\some.dll" KeyPath="yes" AssemblyApplication="some.dll" AssemblyManifest="some.dll" Assembly=".net" />
    <RegistryValue Action="write" Id="someRegistryValue" Key="SOFTWARE\Mircosoft\VisualStudio\8.0\TeamFoundation\SourceControl\Checkin Policies" Name="someReg" Root="HKLM" Type="string" Value="[#some.dll]" />
</Component>

After checking that I had full access to the file, I looked up the issue and found a possible solution on a SE answer, (I've lost the link currently but I will try to find it now) in which it said that the problem was to do with how ligth.exe was compling the assemblies and the suggested editing the .wixproj file and adding;

<PropertyGroup>
    <SuppressAssemblies>True</SuppressAssemblies>
</PropertyGroup>

After doing this the installer was able to compile and build with a warning stating "The command line switch 'sa' is deprecated. (LGHT1108)" after looking this error up I couldn't find any newer or more relevant commands so I decided to test the installer and found that it doesn't work stating that an unexpected error has occured and giving the error code 2228 which relates to a database error.

So my question is has anyone else encountered problems such as this and if so how did they overcome them?

I realise there could be a simple solution to this and an oversight on my part.