wig file generated by MACS doesn`t fit input sam

[tujchl]

HI:
I use MACS to do my peak calling and visualize my results by uploading wig file to UCSC. when I check reads distributution I find a bizarre thing:

below is part of wig generated by MACS:
track type=wiggle_0 name="treated_cells_treat_chr7" description="Shifted Merged MACS tag counts for every 10 bp"
variableStep chrom=chr7 span=10
34041 1
34051 1
34061 1
34071 1
34081 1
34091 1
34101 1
.......

and below is part of sam from bowtie and set to MACS to generate wig above:
HWUSI-EAS455_0024_FC62N0TAAXX:4:51:4046:9759#0/1 0 chr7 34040 255 38M * 0 0 ATCCCCCAAAGCCTGATAGAGAGAAGATGCTCATTAAT IIHIIIIIIIIGIIIIIIIHHEIIIIIIIIIIIIIIII XA:i:0 MD:Z:38 NM:i:0
HWUSI-EAS455_0024_FC62N0TAAXX:4:3:4393:14415#0/1 0 chr7 34809 255 38M * 0 0 ATGAATATTTGCTTCCCCTTCCTAGTGTAATAGAGTAA IIIIIIIIIIIIIIIIIIIIGHIIIGIHIBIIIIEEGF XA:i:0 MD:Z:38 NM:i:0
HWUSI-EAS455_0024_FC62N0TAAXX:4:53:15681:3020#0/1 0 chr7 35541 255 38M * 0 0 TTGGGCAAAGGGAATGAACAGACACTTTTCAAAAGAAT IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIHIIIIIII XA:i:0 MD:Z:38 NM:i:0
HWUSI-EAS455_0024_FC62N0TAAXX:4:110:10526:17907#0/1 0 chr7 35635 255 38M * 0 0 AGAAATGCAAATCAAAACCATAATGAGATACCATCTCA HH@H@GGDGEBDGBBDGEDGGBDBBEDBEBEEGGEGDD XA:i:0 MD:Z:38 NM:i:0
HWUSI-EAS455_0024_FC62N0TAAXX:4:103:15636:4650#0/1 0 chr7 35756 255 38M * 0 0 TGTTGTTGGGTGTGCAAATCAGTTCAATCATTGTGCAA IIIIIIIIIIHIHIIIIIIIGIIIIIIIHIIIIIIIIE XA:i:0 MD:Z:38 NM:i:0

you can see in sam file there is only one read mapping to position 340XX (I sort my sam file), and on wig file there are too many reads mapping to 340XX which can`t explain by reads shift.

can you help me? thanks

[Chipper]

The wig will show the overlap of the shifted extended read for every 10th base, so there is nothing wrong with your file.

[tujchl]

Thank you for your replying Chipper
but I don`t understand you very well.
in the wig file there is one read located on the each bin of 34041, 34051, 34061.....
and there is only one read in sam which can be mapped to this region even after shifting that is 34040. My question is how do the other reads come from on wig file.
and what do you mean by overlap?