use search pipe not working

[React4321]

REQUIRED: Before filing a usage question

Change each [ ] to [x] when you have done it.

• My issue title starts with [usage question]
• I have read the README, especially the 'classic blunders' section
• I have looked at the demos to see if my use case has obvious examples.
• I have searched the ng2-dragula issues, including closed issues.
• I have browsed the issues labeled "future reference" for problems that have been solved before.

Use case description (required)

A clear and concise description of what you want to achieve.

Can you show a demo, or a picture of what you want to achieve?

If so, please link it here.

Additional context

Add any other context here.