Gene expression using ballgown

Hi

I ran this command:

bg = ballgown(dataDir="Ballgown", samplePattern= "*", pData=pheno_data)

Then i got the below error.

Error in ballgown(samples = c(... : intron ids were either not the same or not in the same order across samples. double check i_data.ctab for each sample.

Please assist, how can i correct the files and get it to work?

Kea