Siemens S5 transfering to PLC

Please help, I have a seimens S5-100U cpu100 plc and have sucsessfully transfered the program from the plc using simatic step5 v7. I cannot transfer into the plc I get a error message - block list not in plc. All I would like to do is to add an input in a pb block which i have done, but cannot transfer.

Are you trying to transfer one block or the entire program? Type in the pb block # when you are trying to transfer and it will transfer only that block.

thanks for your reply, I transfered pb1 from plc to pc without problems. Then without changing anything to pb1 when I transfered from pc to plc I get the message - block list does not exist in plc. The cpu is 102 not 100 as stated before.
Also when testing block status i get the message block not processed.

Please help

The reason you see "block not processed" is, in siemens, you have an operational block or OB that is scanned every scan. If you look in OB, you should see a jump conditional or some instruction that jumps to your PB#. Make sure you are dealing with a PB and not a FB. Make sure that you have the correct PB#. Block not on plc means just that,
the block you are trying to transfer is not written to the plc. Keep in mind you can edit the program online. Once you save your changes, you will have to upload the block you made the edit in to your programming device.

The S5-102 processor has 2 modes, an editing mode and a running "Fast" mode. If you have an eprom in the PLC and cycle power, it will go to the "Fast" mode, where you are. It will not let you monitor on line in status mode or make program changes and thus the error message. If you have the eprom, upload the entire program to your programmer from the programming port. Kill power and remove the eprom. Do an over-all reset and then transfer your program back with the modifications. If it fails, fall back to the old program. It will run at about 1/10 of the old speed, but will allow online monitoring. The 102 does not have eprom burning built in and will have to be done offline. Once you get the program the way you want it, erase and re-burn the prom, shut off power, install prom and then you will be back on the road again.