Problem with switching basemap to OpenStreetMap

Question

Hello, I would like to make a map of Tenerife with switching basmaps. But i cant manage to see where is the problem in code, it just dont appear at Run, it appears to be loading but nothing will come up. Wolrd imagery map works fine. 
PS I am a beginner.

Thank you for answering.

Please look attached code.

tenerife_map_code.txt.zip

andreaskiik · Answer

And now it works fine 🙂

Thank you so much for answering.

kenbuja · Answer

The button bar uses a zero based index, so your code show be like this (if Avatud Maakaart refers to OpenStreetMap)