We have already seen that, as early as 1924, Mises had indicated dissatisfaction with Böhm-Bawerk's theory. This may come as a surprise to those who—quite mistakenly—believe that the Austrian position on most questions of economic theory, and especially on the theory of capital and interest, is a monolithic one. The truth of the matter is that, while the suggestive brilliance of Böhm-Bawerk's contribution won international recognition as typifying the work of the Austrian school, it was by no means acceptable to other leading representatives of that school. It is by now well known, as reported by Joseph A. Schumpeter, that Carl Menger considered Böhm-Bawerk's theory of capital and interest to have been "one of the greatest errors ever committed."
Referring specifically not only to Menger but also to Friedrich von Wieser and Schumpeter himself, Hayek remarked that those "commonly regarded as the leaders of the 'Austrian School' of economics" did not accept Böhm-Bawerk's views.
So we should not be overly surprised at Mises' disagreement with his own mentor's teachings.