There's no such thing as a "dual conversion" transmitter. Conversion refers to the filtering that the receiver does after it receives the signal. Both types work from the same signal.

Please double-check that receiver. I highly doubt it says "75MHz." GWS does not make R/C cars, that I know of, yet.

First, are both the receiver and transmitter on the same channel?

Second, did you get a Futaba-compatible receiver? It should have an "F" sticker on it. If it has a "J" sticker, it's JR compatible.

Third, does the transmitter work on other receivers?