[R] problems about dynamic GMM

[97258031]

Dear all, 

I am a new user of R, and I would like to use R to estimate dynamaic GMM of Arellano and Bond (1991).

The package I used is "plm" and its code "pgmm."
However, the regression cannot run and it showed an error message:
"Error in solve.default(Reduce("+", A2)) : 
  system is computationally singular: reciprocal condition number = 2.27327e-27."

Could I please ask, how could I deal with this problems, or are there any other package which can help me estimate dynamic GMM?

Many thanks for help.

--
Hao-pang