One specific weakness of controlling $OV_PRO from the SPS is that, if the SPS is trying to set the SPS to 0% while someone is trying to change the SPS from the pendant +/- softkeys, the KCP display can become "disconnected" from the real value of $OV_PRO. One way to check if this has happened is to open the Variable Monitor and type in $OV_PRO. This will access the real value of $OV_PRO. If this value disagrees with the number displayed in the KCP's upper-right corner, you've encountered this issue.
Another cross-check is to open the Position Monitor while attempting to run the program. If the robot is simply moving or accelerating very slowly, you should still be able to see consistent motion in the Position Monitor. If there is no motion in the PM while the program is running, this strongly suggests that $OV_PRO has been set to 0%, as other posters have suggested.
You are a GENIUS!!!
I set the $OV_PRO variable to 100 and all gone OK!!!
I also tried to change the variable with buttons and check the variable and it works perfectly now.
Thank you very much for you fantastic help.
PS. litte OT ... at the moment we have the ArcTech.Digital 2.3.3... Kuka proposed to switch to ArcTech.Analog. They say that the welding settings can be programmed from the robot directly. Is this true? Thank you very much.