Selecting XVTRs via API commands

I have setup SmartSDR 2.4.9 on my new Flex6600 for 10 vhf/microwave transverters.
I have since before a separate C# application for transverter switching & Az/El control/display.

Now I want to set up SmartSDR for the correct XVTR from my own C# application by adding API
control of  XVTRs.

I have played around a bit with with the K1PGV C# Test program to test commands for XVTR activation. The test software work well but when I add a button for activation of a specific XVTR
nothing happends, no errors. The txtXVTR.Text is updated.

The code I added after the Mode buttons is:

private void btn1296_Click(object sender, EventArgs e)
        {
            _thisRadio.ActiveSlice.Panadapter.XVTR = "1296";
            txtXVTR.Text = "1296";
        } 

Any clue what I am doing wrong?

/Jens SM6AFV


Running the Test software under v3.0.19 did not worked ok so I downgraded to v2.4.9 again