Problems when using FIFO IP for simulation

adc_fifo.v(41): Instantiation of 'adcfifo' failed. The design unit was not found.
I guessing line 41 start from here:

adcfifo fifo(
.data (sink_avalonst_data),
.wrclk (sink_clk),
.wrreq (sink_avalonst_valid),
.q (source_avalonst_data),
.rdclk (source_clk),
.rdreq (source_avalonst_ready),
.rdusedw (rdusedw),
.aclr (~reset_n)
);

Modelsim can't find the so-called adcfifo.v file and I guess the adcfifo.v is in the adcfifo.qip that you generated based on Intel FIFO IP. Add the qip in your project, compile and simulate again.