I am new to WDM audio driver, and I am puzzled in using filter property and pin property in developing the driver. Hope I can get help here. I want to communicate with the driver from user mode application through IOCTL_KS_PROPERTY. In the application, I used setupdixxx and createfile to get the handle to the driver, then used deviceiocontrol to set the property of the pin. In the driver, I declared the automation table in pin descriptor. But calling to deviceiocontrol failed. In the document of DDK, it is said "When a client sends a KS property request (that is, an IOCTL_KS_PROPERTY I/O-control IRP) to a filter handle or pin handle, the KS system driver (*ks.sys*) delivers the request to the port driver for the filter object or pin object." I am wondering in my application, I only get the filter handle through setupdixxx and createfile, so the request could not be delivered to pin object, is that right? If so, how can I get the handle to the pin or send the request to the pin object? Thanks in advance for your help. Yong