Midi Program Changes

I would like to use the Preset Midi Out function to switch the channels of my amp (Engl Amp with Midi Switcher), this also works if I set the bank and the program change number.
However, the problem is that the QC selects the preset the first time I press the footswitch and only sends the MIDI PC when I press the button a second time.
Why is this the case? Is it not possible to set that the preset is changed AND the PC is sent at the same time?