Error when we click on line item of purchase order approval app

Hi,

We have configured the purchase order approval app for my inbox on fiori launchpad.

In the main screen it shows the number of work items to approve.

When we click on the app to the master data list for approval, get an error.

Also when we click on individual purchase order for approval, get the same error.

When I check the error, it says, 'No system alias assigned for user service and SID ' ' CNT ' '.

But system alias is assigned in back end.

Can anyone help us resolve this issue.

Thanks,

San