bug in the /fill command

I have run the commande /fill 73 91 42 73 91 42 minecraft:command_block 0 replace minecraft:air for replace sandstone with command_bock(I have make a tests before)

What I expected to happen was...:
The command owes placed acommand_block

What actually happened was...:
but the command don't place the command block we have an output message: "Data tag parsing failed: Invalid tag encountered,expected "{" as first char."

Steps to Reproduce:
1. run the comrade /fill 73 91 42 73 91 42 minecraft:command_block 0 replace minecraft:air near the coordinate