String Concatenation error in Cygwin bash shell - cygwin

Question

I am having problems concatenate two strings in BASH (I am using Cygwin)
When I am doing it step by step in the cygwin window, it works.
i.e by defining dt=2012-12-31 and c=.txt explicitly and then concatenating in filename=${dt}${c}.
It doesn't seem to work when i am running it through my script where these variables are defined by cutting and assigning values from content of a file.
Though the variables are assigned with the same values as above, the concatenation in this case doesn't work.
instead of 2012-12-31.txt i am getting .txt-12-31 as result.
The code is:
for x in {0..11}
do
IFS=$'\n'
filename=date_list.txt
file=($(<"$filename"))
IFS=$'\t\n'
dt=${file[$x]}
echo $dt
for y in {0..85}
do
IFS=$'\n'
filename=SQL_Mnemonics.txt
file=($(<"$filename"))
IFS=$'\t\n'
Mn=${file[$y]}
for k in {3..502}
do
IFS=$'\n'
c=.txt
filename=${dt}${c}
file=($(<"$filename"))
IFS=$'\t\n'
echo ${file[$k]} > temp_file.txt
cusip=`cut -c11-19 temp_file.txt`
result=$(sh ctest.sh $Mn, $dt, $cusip)
echo "$result" > tmp1.txt
t1=`cut -c18-40 tmp1.txt`
echo $t1 | sed 's/[[:space:]]//g' > temp_file.txt
cat tst.txt | sed 's/-----//g' >> ForFame/${Mn}.${dt}.txt
done
done
done