Problem with syntax highlightning on Xemacs 21.4.13

Hello list,

I've a problem with the sysntax highlightning with Xemacs 21.4.13 on SuSE
Linux 9.0. The problem concerns the latex-mode. Opening a dataset in this
mode, I see the bold font for bold latrex font, the emphasize font for
emphasize font, and so on. However, when I start typing, and enter a new
passage in bold font (e.g. {\bf This is bold}, I have no syntax
highlightning. To get the syntax highligthning for the new passages, I
first must save the buffer, delete the buffer, dan the reopen the file.

Does anyone know the reason for this strange behaviour? And how can in
achieve to get the syntax highlightnng right in time?

Alexander