When playing the Rhumba bass line in the key of G, you should have no problem with the G and C chords, but when you get to the D chord the fingering may require some extra practice. The real problem here is the grace note.
The D note is played with the 5th finger, then the grace note F is played with the 4th finger before playing the F# with the 3rd finger. The final note A is played with the thumb. Practice the whole thing slowly at first.