Issue with Service Manager 9.4 Dashboard Chart

Hi All

I am trying to create a chart on one of my tables 'device' in my service manager 9.4. While creating the report i could see the error saying 'Field subtype not mapped to the database(display, fdisp.1)'.

Here subtype is the field in device table. Also some times I am able to create the report and while clicking on chart i am getting kicked out of service manager continuously.

Can any help on this what could be the issue, i have seen the same issue when change the report with other fields too in place of 'subtype' field example.