Unable to add ssh credential in Jenkins

@Inderpreet, @rahul456

After installing ssh plugin and if we try to add ssh server. Unable to add credential second time. Kindly let me know how to fix this issue

Hello, @nithyaks
What is the ssh plugin name?

just ssh. first time i can add ssh server and credential. After save and try to add another server later. add button not working.

Please find the screenshot. If i click on Add button it is not showing jenkins.