If the switcher jumps between inputs, it is not timed correctly; the switcher's timing window must be sufficient enough to time the Compix system in. To test it, connect your switcher PGM output to a vector scope. Also make sure the switcher or CG and vector scopes are synced properly with analog black.
After setting up the vector scope, toggle the H-Phase (horizontal phase) of the Compix Control program to properly time it in. If the Compix toggles do not work, that means it is not available for adjustment on your switcher or the switcher automatically times it in and will ignore Compix's adjustments. (From your switcher, select black on your PVW and CG graphics on your PGM. Toggle your T-bar on the switcher while adjusting the H-Phase to time it in.)