Hi Sanmeet,
I ran into the same issue but it wasn't related to DTM. It was related to upgrading from H.25 code to AppMeasurment.js. A function that getPageName() relies on was removed in AppMeasurement.js. The code below should help you get the plugin working again if you still need it. the JavaScript below was provided to me by Adobe Support.
To use this, just paste it directly after " function s_doPlugins(s) { "
s.wd=window;
s.fl=new Function("x","l",""
+"return x?(''+x).substring(0,l):x");
s.pt=new Function("x","d","f","a",""
+"var s=this,t=x,z=0,y,r,l='length';while(t){y=t.indexOf(d);y=y<0?t[l"
+"]:y;t=t.substring(0,y);r=s[f](t,a);if(r)return r;z+=y+d[l];t=x.subs"
+"tring(z,x[l]);t=z<x[l]?t:''}return''");
s.rep=new Function("x","o","n",""
+"var a=new Array,i=0,j;if(x){if(x.split)a=x.split(o);else if(!o)for("
+"i=0;i<x.length;i++)a[a.length]=x.substring(i,i+1);else while(i>=0){"
+"j=x.indexOf(o,i);a[a.length]=x.substring(i,j<0?x.length:j);i=j;if(i"
+">=0)i+=o.length}}x='';j=a.length;if(a&&j>0){x=a[0];if(j>1){if(a.joi"
+"n)x=a.join(n);else for(i=1;i<j;i++)x+=n+a[i]}}return x");
s.ape=new Function("x",""
+"var s=this,h='0123456789ABCDEF',f='+~!*()\\'',i,c=s.charSet,n,l,e,y"
+"='';c=c?c.toUpperCase():'';if(x){x=''+x;if(s.em==3){x=encodeURIComp"
+"onent(x);for(i=0;i<f.length;i++){n=f.substring(i,i+1);if(x.indexOf("
+"n)>=0)x=s.rep(x,n,'%'+n.charCodeAt(0).toString(16).toUpperCase())}}"
+"else if(c=='AUTO'&&('').charCodeAt){for(i=0;i<x.length;i++){c=x.sub"
+"string(i,i+1);n=x.charCodeAt(i);if(n>127){l=0;e='';while(n||l<4){e="
+"h.substring(n%16,n%16+1)+e;n=(n-n%16)/16;l++}y+='%u'+e}else if(c=='"
+"+')y+='%2B';else y+=escape(c)}x=y}else x=s.rep(escape(''+x),'+','%2"
+"B');if(c&&c!='AUTO'&&s.em==1&&x.indexOf('%u')<0&&x.indexOf('%U')<0)"
+"{i=x.indexOf('%');while(i>=0){i++;if(h.substring(8).indexOf(x.subst"
+"ring(i,i+1).toUpperCase())>=0)return x.substring(0,i)+'u00'+x.subst"
+"ring(i);i=x.indexOf('%',i)}}}return x");
s.epa=new Function("x",""
+"var s=this,y,tcf;if(x){x=s.rep(''+x,'+',' ');if(s.em==3){tcf=new Fu"
+"nction('x','var y,e;try{y=decodeURIComponent(x)}catch(e){y=unescape"
+"(x)}return y');return tcf(x)}else return unescape(x)}return y");
s.parseUri=new Function("u",""
+"if(u){u=u+'';u=u.indexOf(':')<0&&u.indexOf('//')!=0?(u.indexOf('/')"
+"==0?'/':'//')+u:u}u=u?u+'':window.location.href;var e,a=document.cr"
+"eateElement('a'),l=['href','protocol','host','hostname','port','pat"
+"hname','search','hash'],p,r={href:u,toString:function(){return this"
+".href}};a.setAttribute('href',u);for(e=1;e<l.length;e++){p=l[e];r[p"
+"]=a[p]||''}delete a;p=r.pathname||'';if(p.indexOf('/')!=0)r.pathnam"
+"e='/'+p;return r");
s.gtfs=new Function(""
+"var w=window,l=w.location,d=document,u;if(!l.origin)l.origin=l.prot"
+"ocol+'//'+l.hostname+(l.port?':'+l.port:'');u=l!=w.parent.location?"
+"d.referrer:d.location;return{location:s.parseUri(u)}");
Hope that helps!
