The lab simulation shows me promising but the proof of this Theorem can not be adapted from the old proof
I think what you want to say is:
The lab simulation looks promising but the proof of this theorem can not be adapted from the old proof.
We use the expression "looks promising" (or "seems promising") when we think we are on the right track, but further analysis needs to be done for confirmation. For example, here is a quote from a researcher at Drexel University:
“These results look promising, but we need more trials to strengthen the evidence.”
and an energy study concluded:
The results seem promising but more tests must be done during the second period in order to confirm the first result.
Incidentally, there is no need to capitalize the word theorum, unless you are referring to a specific theorum by name (as in Theorum 7.2, e.g., or the Pythagorean Theorem).