'however not able' is not correct and usable in written English.
You could use 'however unable' instead. For example: Despite his hard work, Bob was however unable to pass the exam.
She was, however, not able to free herself of the epithet of bastard, and her movements were severely restricted.
Owing to the low number of patients, we were, however, not able to evaluate separately the value of the whole ASCT + post-transplant maintenance approach.
They are, however, not able to differentiate cholesterol from other sterols.
We were, however, not able to amplify the pfsr1 full-length ORF (2,322 bp long) from cDNA samples.
The FAFLP method was, however, not able to convey much taxonomical utility sufficient to replace the highly tedious serotyping procedures in vogue.
We were, however, not able to detect a postulated CARD-PYD heterotypic association, indicating that ASC oligomer formation predominantly proceeds via homotypic CARD-CARD as well as PYD-PYD interactions.
We have, however, not been able to prove this.
However, not being able to understand something isn't game over, it's game on.
We have however not been able to estimate the size of such contributions in this study.
In some herds, these control measures have, however, not been able to successfully prevent spread of infections between cows.
We have, however, not been able to confirm a direct effect of fenofibrate on human osteoclasts [ 13].
