Can't use F4 when try to test Z_INPUT_CUSTOMER function module
I'm buy book "ABAP Objects" 2nd edition 2007 and try to make all exampless my self. All my examples have prefix Y (in program already used prefix Z by book authors). When i'm make reservation car example i have trouble to test my example with function module.
Can't use F4 when try to test Y_INPUT_CUSTOMER function module.
And i try to find error in Z_INPUT_CUSTOMERS. Bethween my program and builtint example i found 1 diffirence: built in example have object SREEN 1100 in tree OBJECT NAVIGATOR. When i try to make new srceen happents error (already exist). Because in module declared screen 1100.
How can i fix error?