What theories say about it? (plz see the monthly trend of wage earner's remittance for last 20 months. I also attached monthly trend of International Reserve, Trade Balance and Current Account Balance for last 4 years).
Your answers can be found in the literature section of the attached paper.
I haven't studied remittance issues in Africa. However, my experience in Nepal may offer some insights and suggestions you will find useful. In general, remittances tend to be volatile and, to the extent that they represent a meaningful percentage of the GDP, that causes an immediate problem. What is to my mind more important is the emigration of skilled people that remittances suggest.
Remittances grew very robustly since early 1990s and until 2012-13. If these had maintained a growth rate of even 10 percent, the balance of payments would have been in surplus by another 4 billion dollars in the last three years. A worrying issue is that the falling trend has occurred despite fairly robust increase in the number of people going overseas. This could be due to either a fall in net migration or a reduction in per capita remittance. Given that remittances have helped in poverty reduction, both have implications for poverty as well as employment. If the downward trend continues this would be another constraining factor in our development.
It's not too bad. The world economy will be recover in nearly 10 years and people will can increase in wage earner's remittance.