'main' label of MIPS program is NOT being recognized

.text
.globl main

main:
        lw      $a0 4($a1)      # Put the filename pointer into $a0
        li      $a1 0           # Read Only
        li      $a2 0           # No Mode Specified
        li      $v0 13          # Open File
        syscall
        bltz    $v0 main_err    # Negative means open failed
        li      $v0, 10
        syscall

I have stripped out all code, and .data values that are not relevant to this question. When I run this code, I use the command "spim programName testFile". I continue to get the following error:

The following symbols are undefined:
main

Instruction references undefined symbol at 0x00400014
[0x00400014]    0x0c000000  jal 0x00000000 [main]           ; 188: jal main

I have no idea what could be going wrong.