Greetings!
Sorry for the late reply.
First of all, there could be many reasons:
When you compile a strategy and you want to use this in connection with another strategy you need to have full permission by default.

you see the red arrow for the input of a compiled strategy -> you have to connect these start which are mentioned there to the strategy
Please test it and if it not work please send us the strategy. Alternatively, you can also send the strategy via email.
Thank you!
Cheers