PSO Get Appointment Error

Hi All,

When requesting for slots getting the response as below: 

{
    "@odata.context": "https://elex-fsm-tst.ifs.cloud/OData/$metadata#Edm.String",
    "value": "Error occurred when retrieving Appointment Offers from the PSO Gateway. Please press the \"Get Offers\" button to try again. If this continues to fail, please go to the Schedule Workbench and look at the Events table found within the System tab of the Administration Workspace for more information.\r\n"
}

Any idea on this.

Thanks,

Lavanya