Question [HELP] I9505 network signal problem

Hi, im from peru, recently bought a cell phone model: Samsung S4 I9505 Factory Unlocked (AP:i9505xxuemk8 Modem: i9505xxuamdc CSC: i9505btuemk5) Android 4.3; the phone recognizes my network operator (movistar) without problems but when the phone goes into "deep sleep" mode and i turn on, it loses signal (check images) and the signal returns after a few seconds (or minuts), only GSM Netwotk Mode works fine, please be patient with me, because i'm newbie, thank you.
Attached Thumbnails
Click image for larger version

Name:	Screenshot_2014-04-21-12-16-36.jpg
Views:	78
Size:	143.4 KB
ID:	2700281   Click image for larger version

Name:	Screenshot_2014-04-21-12-17-05.png
Views:	84
Size:	106.0 KB
ID:	2700282   Click image for larger version

Name:	Screenshot_2014-04-21-12-08-24.png
Views:	72
Size:	141.3 KB
ID:	2700283