We have tried plunging, snaking and chemicals in order to solve a drain problem with the toilet and tub in the upstairs bathroom. Nothing works. We also checked the vent pipe on the roof-there doesn't seem to be anything in it.

With the toilet pulled up, the water drains to a certain point and then stops. Water sits in the tub. We can see the water rising in the floor pipe when running in the sink. Then the water overflows from the floor pipe.

Please note that we have a downstairs bathroom also--just a sink and toilet--they are attached to a separate stack pipe. They work fine.

Please note that the house is very old with old plumbing. We have searched all around the outside of the house for a cleanout but can't find one.

Any ideas--anyone?

Call the plumber and tell him to bring his sewer machine.

The plumber might have a jet setter

the plumber might have a jet setter

Huh?

"With the toilet pulled up, the water drains to a certain point and then stops. Water sits in the tub. We can see the water rising in the floor pipe when running in the sink. Then the water overflows from the floor pipe."

This is a no-brainer. The drain line's clogged before it reaches the stack. While you might have snaked the line, the fact that it's still clogged tells me that you didn't run the snake in far enough.
You may snake from the open toilet drain or from the lavatory roof vent but run the snake in until the clog's removed. Good luck, Tom