FIFO Simulation Modelsim Timing Error

[Sahil_Honeywell]

Hi, 

I am writing a simple test bench for 8-bit FIFO. During simulation in Modelsim, when the 'write_fifo' signal turns high, it becomes red (X). Everything else remains fine. The 'read_fifo' signal is fine. Can you please tell me what I am doing wrong and how can I correct it. Please find snapshots and code in the attachment. 

Am I doing something wrong with 'write_fifo' signal with respect to FIFO 'clock'?

[Sahil_Honeywell]

I figured this out. My test bench was wrong. I was triggering write signal instead of read signal in multiple processes. After correction it works fine now.