Certificate is not showing when it is imported from "Import From Keystore" ?

I have one java based server in tomcat.
I have installed self-signed certificate on that.
Now I have created soap webservice client for that server in salesforce.
Some where I have read that I have to install that certificate in salesforce to complete the call.
So I have export that certificate as .jks   file and trying to install it on salesforce instance.
From
Security Controls>Certificate and Key Management>Import From Keystore.
When I am importing that .jks file at that time I am getting below notification
You've created 0 non-expired certificates out of a limit of 50.
I don’t know what is the meaning of this message.
I need to know what I have to do to install this .jks file.
I am not getting any issue while I am installing .jks file which I have generated from salesforce. It is imported successfully.