Issue with prompt and filter panel

Hi Experts,

I am using Filter panel in my dashboard.

When i use  Datasource_name.openPromptDialog(500,500); during runtime it is producing the following error.

but , Application.openPromptDialog(500,500); Works fine.

Since i have many datasources, i am in need to show prompts separately for each datasource.

I Could not find any solution for this . I would be glad to know the reason for this error.

Thanks in advance