7.1.4. Cannot connect these sockets

Read the message that appears when the connection is refused:

• Incompatible socket: the kinds cannot connect, for example audio into MIDI. Add a converter, such as MIDI Decode or MIDI Encode. See Signal kinds and units.
• Choose an input socket as the target or Choose an output socket as the source: drag from an output to an input. Outputs sit on the right of a node and inputs on the left.
• Map Range is locked to …: this Map Range already drives a different kind of destination. Add a second Map Range.
• Polyphony Zones don't take audio input: connect MIDI to the Polyphony Input and build the sound inside the Zone. See Add nodes, edit live, remove a Zone.
• Polyphony Input pitch and gate outputs are per-voice signals: connect them to nodes inside the Zone, and send results out through Polyphony Output.
• … takes its signal type from its input: connect that node's input first, then its output.
• … is controlled by a Macro: right-click the parameter, choose Remove Macro, then connect.

If the connection works but sounds wrong, compare the two sockets' units and ranges. See Read what a cable carries.

Still stuck: check Compatibility and known limitations, then contact support with your DAW version and plugin format.