app2.xlsm

The resolution, to my amazement, is desperate.
By adding
before each time
The error does not emerge.

Very long time age I discovered the "trick" of it, but
I hate using it as I dunno... anyway just thought it was not a proper way to tackle run-time errors. Whenever I couldn't explain why the error exists and find the right way to resolve it, just using a hard way... is not going to help me improve my scripting knowledge a lot.
Anyway, don't know what I'm talking about. If anyone knows why the run-time error exists, please do teach me a thing. Thank you in advance.

P.S.:
Indeed, the error normally emerges 3 - 4 times out of 10 trials.