problem with software trigger in Data acquisition

Hello, I am using matlab for data acquisition from photo diode through NI DAQ, the data acquisition happen for certain set of wavelengths and again the process repeats for several times. In this process, i receive an error mentioned below and the program breaks and measurement stops.

Error using daq.analoginput_nidaqmx_1_625/trigger

OBJ must be running before TRIGGER is called. Call START.

Error in daqdevice/trigger (line 54) trigger( uddobjs );

Error in avg_IR_55_sweep (line 31) trigger(ai) % software trigger to start measurement

I would like to know why this software trigger timeout is happening, and how do i resolve this issue.

Please find the attachment of my matlab program.