multiple bands in eluted product..

Hii all..

  i am doing DNA barcoding of Dipterocarpaceae.( a woody plant species). i extraced DNA from samples using Qiagen kit.Then i did Pcr with rbcL primer (1F/724R). i got amplifiication at 700bp lenth. Then eluted the product using Nucleospin kit. The problem is  the eluted product always containing multiple bands.. How can i rectify this problem..pls give suggestions...