Image Acquisiton Timing Variation

Hello, I am seeing a wide variation on timing issues using the IMAQ (with Genicam adaptor)

     vidobj=app.vidobj1;
     tic;
     trigger(vidobj);   %Requires manual triggerconfig, start(vidobj) continuously passes data from 
                        % camera to matlab buffer. Trigger then extracts the last frame from the buffer          
     pause(0.1);   
     
     %Deal with frames not being available 
     nf=vidobj.FramesAvailable;

     ct=0;        
     while nf < 1
               nf=vidobj.FramesAvailable;
               ct=ct+1;
               if ct > 100
                    ReportMessage(app,'Max Timeout Retries Reached'); 
                    break
               end
                   pause(10/1000);
     end  
     
     frame= getdata(vidobj,1); 
     %[frame,time1, meta]= getdata(vidobj,1);             
               
     dt=num2str(toc,'%.3f');     %Time since trigger started
     ReportMessage(app,['------getFrame Time =',num2str(dt,'%.2f'),'---Frame TimeOut Retries = ',num2str(ct)]);  

My exposure time is set to 0.4s. So my timing dt is before the trigger to after getdata so should be at least 0.4s. However I'm seeing a massive variation.