Order of worksets in left navigation

I am facing a strange problem while ordering the number of worksets in left navigation.

I have a role under which 5 worksets should appear in left navigation as mentioned below

1. TestWS1

2. Test WS2

3. Test WS3

4. Test WS4

5. Test WS5

I have set the sort priority accordingly to show left navigation as per above sequence. But when i view the role, folders are shown randomly.

Can anyone suggest what may be the cause behind it?

Regards

amit