Error in export gst refund filling

Hello Members,

I am applying for a Export GST Refund for April'18 without payment of tax. While applying,get "Error : Kindly file refund application for July,August,September,October,November,December,February 2017-18 before filing refund for April 2018-19". But we already file the refund of July'17 to March'18. if i apply 2017-18 get "Error : A drafted/saved/submitted application already exists for this tax period.."

plz help me..........