Cst return -iii e error

The dealer has been registered iunder Maharashtra and CST in May 2011, in his case Return (231) is applicable six monthly.

While validating CST return (IIIE) , there is error showing Return applicable is quartely as he filing the return first time.

Question:

1. Can his return undre MVAT (231 ) be six monthly and CST Return ( IIIE) quartely, urgent please

2. If  yes/ no, please reply properly to do the needful