Automatically Stop Recording After Some Seconds?

I achieve to record and stop recording (manually with a button).

Now i want somehow to automatically stop recording after some seconds.

I used the following methods which did not work:

1. Used a timer to call the stoprecording function (I found out that while recording the timer did not work) I tested it with an msgbox and i was right, the msg box appeared 5 secs after pressing the stoprecording button!!!!

2. Used the System.Timers.Timer but nothing

3. I tried the CAPTUREPARMS structure but i`m doing something wrong and it doesn`t record.

Here`s my initialization:

Dim MyParams As New CAPTUREPARMS
With MyParams
.dwRequestMicroSecPerFrame = 66667

[Code]....