median is misspelled...
What do you want/expect as a result? Logicals don't work that way; you'll have to test for each level.
As written, even if the logical test worked, you would only have a '1' in the Msc array for all locations which had a value greater than the least of those in your list of various t* -- not a way to locate which would be greater than each threshold. To do that you would need to be able to store a logical plane for each of the levels--6 total so would need a r x c x 6 3D array.
The way to do something like this in ML would be to loop over the number of levels and do the logical test as vector operation. Something otoo--