Mr.Chris,
Thanks for your reply.
I cudn't uninstall the first reports instance.So created a new instance and reinstalled OTM choosing the Report Server option.
Installation is successful.After starting all the services,when I try to generate a report,I got the following error.

REP-51002: Bind to Reports Server
rep_hydhtc137458d_frhome2.DomainName failedThe entries in the glog.properties are as follows# external Oracle Reports Server - optional
report_feature=true
p_reports_server=REP_HYDHTC137458D_FRHOME2.DomainN ame
p_reports_out_dir=D:/OTM55/rptapache/htdocs
reports_server_fqdn=http://hydhtc137458d.DomainName:7777/reports/rwservlet
report_server_url=http://hydhtc137458d.DomainName:81
#discoverer_url=Any suggestions pls..Thanks,
Durga