[NTG-context] output of the table is wierd

Dear all, I made a column as following: … \starttabulate[|c|c] \HL \NC $\sim (p \vee q)$ \VL $\sim p \ \wedge \sim q$ \NC\NR \HL \NC $\sim (p \ \wedge q)$ \VL $\sim p \vee \sim q$ \NC\NR \HL \NC $\sim (p \to q) $ \VL $p \wedge \sim q$ \NC\NR \HL \NC $\sim (p \leftrightarrow q)$ \VL $(p \ \wedge \sim q) \vee (q \ \wedge \sim p)$ \NC\NR \HL \stoptabulate … The first column is OK. But lines in the first three rows in the second column expanded to the width as wide as the last row. So the it looked very strange. Is there a way to avoid such a bad looking output? I am using latest luatex and ConTeXt stand alone in OSX. Thank you. Best regards, Dalyoung