I am writing an ASP.Net application which uses the Lync client API to get user availability state from Lync.
Now I get a strange error when calling the Lync api methods:
"The file or assembly 'Microsoft.Lync.Model [...] not found".
But I have referenced the Lync client api in the correct version.
What do I have to change to make this working?
The Lync client api may not be an ideal fit for an ASP .Net application but that depends which of the 2 you are using.
There is one for desktop applications and one for Silverlight applications, see https://msdn.microsoft.com/en-us/library/office/jj933180.aspx for more details.
Regardless of which version you are using you will need the Lync client installed on that machine. To be explicit if you are using the api on the server as I suspect then the server will need the Lync Client installed there.
It's also worth noting that there is a web api for lync https://msdn.microsoft.com/en-us/library/office/dn962133(v=office.16).aspx