If there are error, NVS shows Error code(8 digit Hex number) on the LCD.
What is the error code you see on the LCD?
Is that error happen when you connect memory card?
Or error happens during the copy?
There can be following issue.
1. NVS1501 supports FAT file system only. Or exFAT file system with file size smaller than 4GB.
So if your CF card contains file size larger than 4GB, then it will make error.
To copy file size larger than 4GB, we have NVS2801+ or NSB-25 or NCB-20.
2. If CF connector pin bent, then it will make error during CF card detection.
Check carefully if the CF pin bent or not. If bent, straiten the pin will solve the problem.