I'm assuming your trying to program the chip using ICSP. I'll also assume you're using the PGD and PCD lines for something in addition to ICSP. If you isolate those lines using a switch to disconnect them from your circuit during programming and then reconnect once programming is complete then ICSP should work. You could also switch the MCLR line if you wanted but I've found that is often unnecessary.

Something to try is put your PIC back into your demo board and see if it will program. If it does then I'm guessing your programming lines are loaded. In lieu of a schematic and/or code, that is my best but not only guess.