Why Lyx always adds additional columns in arrays when opening?---A bug?

[Qingchang Zhong]

Hello,

I have a problem with arrays in Lyx. Frequently, I need insert vertical and horizontal lines into arrays. For example,
A   0    | 0
0    A   | 0
________
0    0    | A
 

The corresponding latex code is :

\( \left[ \begin{array}{cc|c}
A & 0  & 0\\
 0 & A & 0\\
\hline 0  & 0  & A
\end{array}\right]  \)

I could do this on digital workstation (alpha) before, but now I changed to  a new computer. When I open the file including such arrays,  it always adds additional columns in the array like this:

\( \left[ \begin{array}{cc|c}
A & 0  & 0 & \\
 0 & A & 0 & \\
\hline 0  & 0  & A
\end{array}\right]  \)

When compiling it, the following error:

extra alignment has been changed to ...

comes out and then it stops.

I have tried many versions of  Lyx, 1.0.1,1.0.4,1.1.5,1.1.6... all like this. Now I moved to PC, it still exists.

I think it is because  Lyx reads cc|c as four columns when opening the file but three columns (which it should be) when compiling.

Please help me to solve this urgent problem.

Thanks a lot,
Qingchang