don be sad....everything take time. It is common many will ask and will not buy immediately due to many causes.enquirer to your mail may come from many sources for example A compatitor,A enquirer for cheap price,An enquiry for future purchase,
And usually if after some correspondence and still the buyer did not buy it may be due to many factors:
1/theseller may be bad or poor in proper reply to satisfy the buyer doubt
2/usually the buyer feel the seller may not provide good after sale service and the prospective buyer will not buy.
i guess there are many point on why the seller did not get buyer to respond and the reason can be many.But don worry all you need to do is 1/is your price competative,good service can be given to your prospective buyer if they buy,good level of communication with the prospective buyer,are you responding to their enquiry quickly and precisely(accurately)etc
finally is be patience............
yes first order and all new email is always difficult.