robustse <- vcovHC(mymodel, method = "arellano", type = "HC1") propts out an error

Hi !
I estimated my model using plm (i have a panel datase)
then I tried to compute:
robustse <- vcovHC(mymodel, method = "arellano", type = "HC1")
and the following error emerged:
Error in tind[[i]] : subscript out of bounds
Could you help me please?