That is not correct. All of the NI-USRP API VIs that existed in older versions are still present in newer versions. I'm assuming, Chen, that you mean niUSRP Fetch Rx Data (poly).vi (or niUSRP Fetch Rx Data (CDB/I16/CDB WDT/...).vi). These VIs are installed by NI-USRP 1.3.
I believe the problem is that you are using 64-bit LabVIEW. The NI-USRP driver does not support the 64-bit version of LabVIEW. So the VIs are not installed to the 64-bit LV directories and the niUsrp.dll will not load in a 64-bit process.
You can still use NI-USRP on a 64-bit system, but you must use it from a 32-bit LabVIEW process.
NI-USRP 14.0 will fully support 64-bit LabVIEW 2014. This driver version will be released very soon.
Patrick