If you do a search of the forums for "error 50103" you'll see it is a common question and have an answer. Yes, it is because of the sample clock. You can't start two different tasks on the same device like you did. Combine those two channels into one task.
Fix that first, then maybe the -200290 error will go away also. If not, then it has something to do with the timing of your loop or the regeneration mode of your task. There are examples in the example finder for DAQmx Analog output non-regeneration you should look at.
PS, instead of a 1 iteration while loop to turn a scalar into an array, you should have used Build Array. But actually, if you were only working with 1 channel, you could have used 1 Channel N Samples form of DAQmx Write then you could have wired in the scalar directly! But that will all go away once you fix your code so there are two channels in one task. Then you'll combine your two waveforms into a 1-D array using Build Array and feed that into N channel N samples.
