Problems adding a parameter for logging

Hey guys,
i wanted to add a paramater to the Log.cpp in Log_Write_Optflow (px4flow generated (over i2c send)).
But i always encounter this problem:
Finally I added the paramater (optTime) to the end of the struct ‘optical_flow_s’ in AP_OpticalFlow_Linux.h (also in i2c_frame etc). Then i get the error in the update function of AP_OpticalFlow_PX4.cpp, which is:
/ardupilot/libraries/AP_OpticalFlow/AP_OpticalFlow_PX4.cpp:71:32: error: ‘struct optical_flow_s’ has no member named 'optTime’
state.optTime = report.optTime;

Can sbdy help me on this?

Best regards