[NTG-context] math symbol \doteq cause error in mk||

Hello, I use the context minimal with updating to lastest beta. when using $\doteq$ in my equation, texexec catch an error: ! Illegal unit of measure (pt inserted). <to be read again> = \buildrel ...mathrel {\mathop {\kern \zerocount #2 }\limits ^{#1}} l.3 Test $\doteq $ ? I check the definition in math-pln.mkii, the \doteq is defined as: \def\buildrel#1\over#2% {\mathrel{\mathop{\kern\zerocount#2}\limits^{#1}}} \def\doteq {\buildrel\textstyle.\over=} The problem seems caused by \zerocount. After comparing with the definition in math-pln.mkiv, I changed it to \zeropoint and texexec run successfully. Regards, Andy